In Asia and Africa, sweet potatoes are regarded as one of those foods that need no adornment. In fact, street vendors sell whole sweet potatoes—steamed, baked, grilled, or roasted—to passersby who enjoy their earthy, sweet complexity out of hand, skin and all. Americans also eat sweet potatoes cooked every which way, but we tend to pile them high with a slew of extras—like marshmallows, orange juice, brown sugar, curry powder, cinnamon, or nutmeg—that overpower their taste.
Some cooks riff on butternut squash soup and turn sweet potatoes into a creamy puree. But, like other types of sweet potato dishes, the soups I tried were so loaded with extras that it was hard to identify the main ingredient. I wanted to strip away the nonessentials to make a silky, luxurious soup…
