Carla Lalli Music, a food writer and editor, is vehemently opposed to roasting sweet potatoes. “I don’t understand why people are constantly roasting them,” she says. “Roasting just makes them more fibrous and leathery, and they never, ever really get crispy.” Instead, she posits that steaming performs a kind of alchemy on sweet potatoes that roasting never does — the moist heat fluffs them into absorbent clouds. And to make up for the inherent blandness of the cooking method, she slathers…