Sometimes called a yam, sometimes called a sweet potato, the sweet potato is actually neither a yam nor a potato.
Yes, it’s true. All three are basically underground organs where plants store their starch. But that’s about where the relationship ends.
Yams are tropical “tubers,” the place where tropical grass and lily plants hold their starch, and are native to Africa, South America and the Pacific. They come in varying textures, colors, sizes and flavors and have been know to grow up to 6 feet (yes, 6 feet) in length.
Potatoes, on the other hand, are tubers of a stem plant that bears yellow or silver flowers and are native to moist, cool regions of Central and South America.
So then what is a sweet potato, that wonderfully syrupy starch that so many of us eat at holiday dinners, often adulterated with a hefty dose of marshmallows and brown sugar?
Sweet potatoes are actually root vegetables — which are similar to but different than tubers — and are the storage root of the Ipomoea batatas plant (helloooo botany). They are native to northern South America, but today China is the sweet potato’s biggest consumer and producer.
There are a slew of different varieties: some dry and starchy, others moist, some deep orange or purple and others pale yellow. The “garnet” and “jewel” variety are the kinds you find most often in the supermarket, usually labeled as “yams,” which — as we have just established — they are not.
So…why do we call them yams?
There are a couple of theories. The prevailing one seems to be that yam is a derivative of a Western African word meaning “to eat” as well as the word for true yams (“nyami” and “anyinam”). African slaves brought to America started calling sweet potatoes “yams,” the term spread and then in the 1930s, food marketers ran with it, promoting sweet potatoes as yams in their advertising campaigns. To me, that’s sort of like saying, “Hey, let’s promote turnips by calling them parsnips!” But whatever, clearly I don’t think like a food marketer…
Happily, they got the “sweet” part of the sweet potato’s name right. There’s an enzyme in sweet potatoes that, when heated, breaks down all that starch into a sugar that’s about a third as sweet as table sugar. So the longer you cook those babies, the sweeter and lovelier they will taste.
Boiling or steaming will cook them too fast and you will lose some of the sweetness. But if you roast them…mmm. You will be rewarded with a delicious, soft and mouth-watering accompaniment to any fall meal, no sugar required. And if you whiz them in a food processor with some vanilla-infused half-and-half, butter, salt and pepper? Sweet heaven.
So whatever you call them, if cook them right, you’ll be in for a treat.
Vanilla Bean-Whipped Sweet Potatoes
Adapted from Food & Wine, December 2005
Note: The original recipe calls for heavy cream, but I used half-and-half this time and it was just as good. You could even use whole milk, but I would not recommend low-fat or skim. The aromatics in vanilla are fat soluble, so you will lose a lot of the flavor.
4 lbs sweet potatoes (I prefer the garnet or jewel varieties)
1 cup half-and-half
4 tablespoons butter
1/2 vanilla bean
Kosher salt and pepper
Preheat the oven to 400F. Poke the sweet potatoes all over with a fork and place on a baking sheet. Roast them until they are extremely tender, about 35 minutes — they should give easily when poked with a fork. Let them cool slightly.
Meanwhile, while the sweet potatoes are roasting, place the half-and-half and butter in a saucepan. Split the vanilla bean down the middle and scrape the seeds into the half-and-half. Add the pod to the saucepan and bring the mixture to a simmer. Remove from heat and allow the vanilla to steep in the liquid while the potatoes finish roasting, stirring occasionally so that you don’t get a weird film on the surface. Remove the pod and rewarm before proceeding.
When the potatoes are cool enough to handle, cut them in half and scrape the flesh into a food processor. Puree until slightly smooth. With the machine running, slowly add the vanilla cream and process until completely smooth. Add salt and pepper to taste, scrape into a bowl and serve. The puree can also be refrigerated overnight, making it a perfect make-ahead dish.
Yield: 10 servings