How sweet can a sweet potato be? This may be my worst pun yet but ain’t it just true? A scrubby diminutive root at first glance, dig deeper and a golden treasure reveals. Few vegetables can be as delicious even when eaten plain.
Sweet Potatoes (Ipomoea batatas) are members of the morning glory family native to Central and South America. It is one of the oldest vegetables cultivated by man – traces of 10,000-year-old wild sweet potatoes have been discovered in Peruvian caves. It is believed that Christopher Columbus introduced sweet potatoes to Europe after his first voyage in 1492, and from there they quickly spread to Africa, India and the Southeast. They are now grown in tropical climates worldwide mostly for their delicious and nutritious roots. With over 400 varieties, they can be differentiated by their myriad skin and flesh colour, ranging from pale cream, ginger yellow and feisty orange to mysterious purple.
In the United States, sweet potatoes are used interchangeably with yams, although botanically both are as different as apples and oranges. African yams, related to lilies and grasses, are bigger, heavier, starchier, generally white-fleshed and grow above ground. The confusion between the two started in the U.S. in the Antebellum era. The common varieties of American sweet potatoes at that time were white-fleshed, so when a new variety of orange-fleshed sweet potato was introduced, the name “yam” was commercially applied in order to distinguish it from the others (even though yams are usually white-fleshed). “Yam” is derived from the African Fulani word nyami meaning “to eat,” referring to a true yam, a root crop native to Africa and Asia. There were no nyami in America at the time: African and Caribbean immigrants wouldn’t cause import of real nyami to America until the latter 20th century. But when it was finally introduced, the misnomer stuck.
Sweet potatoes aren’t started by seed like most other vegetables, they’re started from slips – shoots that are grown from a mature sweet potato. As Europeans colonized the Southeast they cultivated sweet potatoes in earnest. Easy to grow and store in warm climates and full of important nutrients, the sweet potato became an extremely important source of nourishment in the Southeast during wartimes. For example, it became the staple diet of many families during the Japanese Occupation of Singapore when there was a shortage of rice. Despite being an integral part of food culture, the sweet potato’s popularity has declined over the last half-century from over 30 pounds per person per year in 1920 to less than four pounds today, perhaps due to its association as a hard-times food.
The yellow spuds are often drier and more dense and starchy than the orange. The orange ones are moister and just a little sweeter. While we are often like bees, selecting the brightest colors hoping for the sweetest nectar, don’t overlook the white and yellow ones. I like to harness each of their goodness in different recipes.
Selecting the best
Choose small-to-medium size sweet potatoes with unblemished skins, avoiding those with black spots or soft patches. Small spuds tend to be more tender when cooked. The following varieties can be easily found in Singapore supermarkets
- Vietnam Japanese sweet potato ($2.20 per kg) – purple skin, yellow starchy flesh
- Australia Gold ($5.50 per kg) – reddish skin, orange moist flesh
- Japanese Annou imo ($4.90 per packet) – smooth russet skin, resembling a mini fingerling potato with golden orange fluffy flesh
- Malaysian purple sweet potato ($6.90 per packet) – purple skin, purple flesh
Store sweet potatoes in a cool, dark and well-ventilated place; do not store in a plastic bag, and do not refrigerate. If refrigerated, their natural sugar will turn to starch and ruin the flavour. Use within 10 days of purchase (or end up with sprouted sweet potatoes). If you do really end up with sprouted sweet potatoes, waste not, because they are still safe to eat. Unlike sprouted potatoes with ‘eyes,’ sweet potatoes belong to a different family and do not produce the toxin solanine.
Scrub skin well to remove dirt. You may keep the skins on or peel, depending on the cooking method. Usually I keep the skins on for convenience purposes as they can be easily slipped off after cooking. As sweet potatoes discolour quickly once peeled, use them immediately after peeling them. If this is not possible, to prevent oxidation, place in a bowl covered completely with water until ready to use.
Sweet potato is very versatile and can be steamed, roasted and enjoyed whole or mashed. My most favorite way by far is to slow-bake a bunch to induce a caramelized sweetness, turning the humble root into a fluff of creamy bone-sticking lightness, if all the paradoxes in the previous phrase actually exist. Sweet potatoes are so delicious just as they are, they really don’t need to be turned into anything fancy or garnished with extra toppings. Nevertheless, their naturally sweet-spicy flavor is immensely enhanced by a range of warm spices, including cinnamon, garlic, ginger, curry powder and maca root powder. It is also heavenly with coconut and all nut and seed butters. Big handfuls of chopped parsley or cilantro with lemon can add a zesty punch too. Don’t overlook the new leaves on stem tips, which make excellent cooked greens.
Bake: simply wrap the scrubbed potatoes in aluminium foil and place in a 425°F or 220°C oven for 40 minutes. Test for doneness by inserting a clean skewer through. They should give easily and feel soft. Another way is to bake them in fries form. Peel and slice them about 1/4-inch thick. Brush them with a little oil (I love using coconut for their heady fragrance; works magic with sweet potatoes) and put them on a lightly oiled baking sheet. Bake at 400°F or 200°C for about 20 minutes.
Steam or slow cooker: slice the sweet potatoes about 1/2-inch thick and put them into a steamer basket or slow cooker. Steam for 10 minutes or cook on low in the slow-cooker as a stew with other ingredients (no time-limit).
Raw: sweet potatoes, both the yellow and the orange varieties, can be shredded and added to salads. They can also be juiced or added to raw soups. Bright yellow or orange shredded sweet potatoes make the perfect garnish to a raw soup or salad topping.
As sweet as they are, sweet potatoes are a superfood. These tubers are rich in fibre, beta-carotene, vitamins C and B6, potassium and manganese and an excellent source of low-GI carbohydrates. This means they are a good choice for diabetics. Beta-carotene is converted to vitamin A in the body, necessary for normal vision, cell growth and cell renewal for healthy skin, hair and eye health. Food sources of beta-carotene are the best way to get vitamin A, since extremely high doses of pre-formed vitamin A in supplements can cause serious health problems. Since the absorption of carotene in the body is optimised when the food source it came from is pureed and eaten with fats, try serving a sweet potato coconut pie or smoothie for readily bioavailable nutrients.
Recipe notebook & inspiration
Beverages: Warming Sweet Potato Smoothie
Breakfast: Sweet Potato Bread
Starters: Sweet Potato Fries | Sweet Potato Hummus | Sweet Potato Falafels | Sweet Potato Energy Bites
Mains: African Sweet Potato, Adzuki & Peanut Stew | Chickpea & Sweet Potato Ravioli
Desserts: Sweet Potato Soft Serve | Sweet Potato Dulce De Leche | Ondeh Ondeh | Bubur Cha Cha | Sweet Potato Brownies
Image courtesy of Rikki Synder.