Ingredient for the Holidays: Okinawan Purple Sweet Potatoes

Memories of Thanksgiving and Christmas dinner for many, may mean rows of classic dishes from turkey stuffing and pumpkin pie; or it may be a table full of sticky rice, soy-braised short ribs and other Asian-style dishes. Perhaps there are a bit of each. But this year, we’d like to bring the two cuisines together into one fabulous creation with the Okinawan sweet potato—our ingredient of the month for November. It’s a beautiful food that lets us take a traditional American Holiday side-dish and re-create it with an Asian twist.

Yam I am?

There is always the confusion as to what the difference is between yams and sweet potatoes. If you don’t already know, authentic yams are uncommon in the U.S. They come from the genus Dioscorea, while sweet potatoes are from Ipomoea batatas. Here are some distinctive properties in comparison, according to an article published by the North Carolina Cooperative Extension Services:

Native to the Old World, the purple sweet potatoes traveled to the New World simply as “potatoes” before what we now associate as a “potato,” the white-fleshed ones used for fries, stews or as a mashed side. When the white-starch tubers were introduced, they were given the same name, “potato”, and the original varieties began to be distinguished as “sweet potatoes”, rather than vice versa.

In the United States, firm varieties of sweet potatoes were produced before soft varieties. When soft types began to be commercially grown, there was a need to differentiate between the two. Here’s where it gets confusing: there seems to be two versions as to how the sweet potatoes were mis-labeled. The first explanation is that enslaved Africans had been calling the “soft” sweet potatoes “yams” because they resembled the West African nyami, the Senegalese term for the large starchy African tuber from the Dioscorea family. When cooked, those in the “firm” category remain firm, while “soft” varieties become soft and moist.

The other more popular story is that in the 1930s, Louisiana farmers chose the word “yam” to set their product apart from the dry-fleshed, pale yellow sweet potato grown in the North, to try to sell more of their sweet potatoes—it was basically a marketing ploy! The name still sticks to this day: In American markets today, “yams” refer to the “soft” sweet potatoes with bright orange meat. The most popular “yam” to date is the Beauregard, which is uniform in size and shape with smooth skin and deep orange flesh. In most cases, when you find something called a “yam” in the markets, it isn’t a real yam, as this type is only occasionally imported from the Carribbean and is, as mentioned above, rarely grown in the continental U.S. However, if you are in search for some, it tends to be sold at Latin-American grocery stores. There are about 150 varieties grown world-wide and yams can grow over seven feet in length.

Nowadays, the U.S. Department of Agriculture requires labels with the word “yam” to be used in conjunction with the term “sweet potato.” Though in trying to dispel confusion, actually adds more to the mis-labeling.

To sum this all up, sweet potatoes are not yams and vice versa. Sweet potatoes are now cultivated throughout tropical and warm temperate regions wherever there is sufficient water to support their growth. According to 2004 statistics by the FAO (Food and Agriculture Organization of the UN), China is the largest grower of sweet potatoes—it grows 100 varieties of sweet potato and provides about 80% of the world’s supply. Historically, most of China’s sweet potatoes were grown for food but now approximately 60% are cultivated to feed pigs. The rest are grown for human consumption and other products. Some are grown for export, mainly to Japan. But in general, over 90 percent of the world’s sweet potatoes are grown in Asia.

About The Non-Spuds

Now with all this information about the differences between yams and sweet potatoes, we have another rather interesting fact: the yam and the sweet potato are neither part of the same family as the white potato, which comes from the Solanaceae (Nightshade) family. Surprisingly, the sweet potato is closely related to the water spinach—both of which belong to the Convolvulaceae family of herbaceous roots and vines. Also noted above, yams are from the yam family, where there are 600 different species of its kind and this includes the Pilipino ube, a purple yam often mistaken for the Okinawan sweet potato.

Sweet Potato Focus: The Okinawan Specialty

In 1605, the Okinawan potato was introduced to Japan from China. A number of varieties were grown, but the Okinawan purple sweet potato—also referred to as tumai kuru or beni imo—became extremely popular, where the typhoon-resistant plant became the mainstay that rescued many from famine in southern Japanese islands when natural disasters struck. The leafy tops are also cooked and eaten as a nutritious green vegetable, while the purple potato is a favored ingredient for chips, cookies, pies and ice cream.

Outside of Japan, the potato is grown primarily on the Big Island of Hawaii. Okinawan potatoes are often confused with a purple sweet potato variety grown on Molokai that has reddish skin and a dark lavender interior, as well as the Pilipino purple ube.

Ok, enough about the appropriate scientific terms, origins and comparisons. What’s so special about the Okinawan potato? When you think of naturally purple foods, the voluptuous eggplant or oval grape is likely to come to mind. But unlike these two, it’s the meat of the Okinawan potato that’s purple, not the skin. The outer layer of the Okinawan sweet potato is ultra thin and light-tan in color. Its flesh is a gorgeous lilac hue with pearly-white veins when uncooked and the scent is reminiscent of fresh-peeled lychee. When cooked, the shade turns a deep plum/lavender with a light, earthy fragrance. Its flavor profile is creamy, sweet and rich; its texture dense and moist.

Okinawan purple potatoes are an excellent source of vitamin C, dietary fiber and antioxidants. That’s why they’re a particularly healthy food to keep sweet-tooth cravings at bay; plus, they can be easily cooked in a multitude of ways traditional potatoes are prepared—roasted, baked, boiled, fried and et al. The sweet potatoes may be peeled before or after they are cooked.

Purple potato ice cream is a very popular treat in Hawaii and Japan, probably because these roots are easily cultivated on these islands. In Japan, they are also customarily boiled, cut into blocks, mashed and eaten plain. At restaurants, you may also find it combined with fresh grated ginger or sesame seeds. These royal-colored beauties are also fabulous in savory dishes such as breads, tempura, croquettes and stew. Other flavors that pair well with the potatoes include: bourbon, brown sugar, honey, orange zest, pecans and rum.

In the U.S., Okinawan potatoes are occasionally grown in California, and may be found in specialty markets on the West Coast—mostly in ethnic markets. When selecting, choose potatoes that are firm and small to medium in size, avoiding those that have wrinkled skins, soft or brown spots, or sprouts. They may range in size from small, thin finger potatoes to large, bulbous tubes. The varied sizes and shapes are due to different weather conditions and factors that limit crop yield, so various grades of potato may be available. Select potatoes that are similar in size for uniform cooking. They must smell fresh and should be crisp when cut open. Due to their high sugar content, store the potatoes in a well-ventilated, dark, dry place and use them as soon as possible. Their quality starts to diminish after 2 weeks. Okinawan sweet potatoes are generally available year-round, but their peak season runs from September through the end of the year.

Recipe: Asian-Fusion Sweet Potato Pie

Make this holiday season a little different this year with a special fusion treat—purple sweet potato pie with coconut whipped cream and caramelized macadamia nuts. It’s a simple recipe that gives the classic sweet potato pie a glamorous and palate-pleasing make-over. Can’t find Okinawan sweet potatoes in your local supermarket? Go to the nearest Asian market and don’t be afraid to ask for Japanese sweet purple potatoes. Still no luck? We get ours from Melissas.com. They ship quality produce all over the nation in almost no time so you can have purple sweet potato pie on the table for the holidays or for any occasion that calls for an eye-pleasing and delicious treat.

If you do a little research on the internet on these purple potatoes, you’ll find a handful of recipes for the purple potato pie and they all vary. We created our own variation that brings out the natural sweetness of the potatoes with a creamy consistency and rich finish that’s matched with other exciting flavors. Feel free to explore your creativity by serving the pie in your preferred way or let guests decide what they want.

So this year, amaze guests with a completely different kind of sweet potato pie—we’ll call it a fusion Thanksgiving dessert or dish—the beautiful color will be its first wow-factor but the simplicity yet richness of the pie’s flavor combinations will win you more compliments than you may be able to take. You don’t even have to tell them where you got the recipe. It’ll be our secret.

Asian-Fusion Purple Potato Pie

Ingredients

• 2 cups Okinawan sweet potatoes, cooked and whipped
• 1 stick of unsalted butter at room temperature (Do NOT melt, it changes the chemistry of baking!)
• ¼ cup granulated sugar
• ¼ cup honey (It’s better to use high quality ones with flower undertones—you’ll taste them in the pie)
• 2 eggs at room temperature
• ½ cup heavy cream mixed with and ½ cup milk
• 1 teaspoon vanilla
• ¼ teaspoon salt
• 1 9-Inch Philsbury Pie Crust (or look for a basic pie crust recipe)

Directions

1. Peel the potatoes and cut them into medium-sized chunks (like half a kiwi). If peeling before cooking, use a vegetable peeler or sharp knife to remove the skin and discard. If peeling after cooking, cut the sweet potato open and scoop out the flesh.
2. Put potato chunks into boiling water and cook until soft. Drain and place in a mixing bowl and whip on high speed. The potatoes should be smooth, like finely mashed potatoes.
3. You need to have at least 2 cups worth of potatoes (judge depending on the size of your potatoes). If you aren’t sure how to gauge the number of raw potatoes to cups, it’s better to cook more than needed.
4. In a separate mixing bowl, cream together butter and sugar. Add the honey and blend well. Then add eggs, one at a time.
5. Next, whip in the purple sweet potatoes. Combine milk, vanilla and salt with the rest of the blend. Continue to mix until well combined. Mixture should resemble the consistency of whipped waffle batter.
6. Arrange pre-made pie crust in pie dish, making sure the entire dish is layered and the crust is slightly folded over the rim.
7. Pour pie contents into crust and bake at 325°F for 30 minutes. Remove from oven. Set aside to cool to room temperature.
8. Choose between making the coconut whipped cream or the crème coconut to pair with the pie. Assemble pie and serve!

Caramelized Macadamia Nuts

Why It’s Needed: It adds the crunchy texture and roasted caramelized flavor to the entire ensemble—think of it as the finishing touch or a garnish.

Ingredients

• 6-8 ounces of macadamia nuts
• ¼ cup sugar
• ¼ water
• 3 tablespoons honey

Directions

1. Preheat oven to 350°F.
2. Pour macadamia nuts into a large bowl.
3. Line baking pan with foil and lightly oil.
4. Bring sugar, water, and honey to a boil in a small saucepan over moderate heat, stirring until sugar is dissolved.
5. Pour over nuts and stir until nuts are well coated.
6. Transfer nuts with a slotted spoon to baking pan (discarding syrup) and roast in 1 layer in middle of oven, stirring nuts occasionally, until golden brown, about 10 minutes. Make sure to check on them every few minutes because they burn very easily.
7. Spray oil onto another sheet of foil, transfer over and spread nuts in 1 layer and let cool completely.
8. Break apart any nut particles and chop until desired nut topping size.

Coconut Whipped Cream

Why It’s Needed: It provides a creamy milk flavor accented with the tropical coconut undertone that complements the pie’s sweet, earthy profile.

Ingredients

• 1 cup heavy cream
• 1 tablespoon coconut liqueur (e.g. Malibu rum)
• 2 tablespoons confectioners’ sugar

Directions

1. In a medium bowl, beat 1 cup of heavy cream until thick and frothy.
2. Add 1 tablespoon coconut liqueur or Malibu rum and 2 tablespoons confectioners’ sugar and beat until soft peaks form.

Alternative: Crème Coconut (for a coconut sauce to dish onto the pie plate instead of a whipped cream on top of the pie)

Ingredients

• 1 cup coconut milk
• 1 tablespoon sugar
• 1 teaspoon flour
• 2 tablespoons of sugar
• 1 teaspoon salt

Directions

1. Simmer coconut milk in pan
2. Mix 1 tablespoon of sugar and flour together; whisk this combination into the milk
3. Bring to a boil.
4. Remove from heat and cool to room temperature and then add salt and the 2 tablespoons of sugar.

If you have a special Asian ingredient that you want to see re-created with an Asian-American spin, please e-mail melody@asiancemagazine.com

Melody has been a food enthusiast since she was a baby who was fed Formula—she threw it up every time, and while doctors claim it’s a common problem in infants, many people believe it’s because she was born to be a “picky eater.” She also grew up loving to write, especially about food, and went on to receive a B.A. from U.C. Berkeley. Her last position at a food magazine allowed her to live out her then dream job of eating fancy foods everyday and critiquing their flavors and textures for articles. Now, she is a freelancer in New York City, pursuing her next career goal of capturing the lives of chefs through photography and writing as well as inventing Asian-fusion recipes for *Asiance*. Melody considers herself the opposite of a food snob—she enjoys eating most anything at any time of the day (chocolate croissants for dinner are as good as prime rib for breakfast) and loves to try new restaurants. Her life revolves around eating good meals with people she can have great conversations with. She believes that fine food is the gateway to encouraging people to appreciate and learn more about different cultures.