We all adore certain pantry staples. Kefir and crème fraîche are two of my favorites. I’ve been testing new ways to improve on roasting sweet potatoes in the oven, and I found that a combination of steaming and roasting works great for a dish like this for both the texture and the extra set of aroma molecules that comes through. The first step, partial steaming, keeps the moisture inside the sweet potato while cooking, and the second step, uncovered roasting, helps create a robust flavor profile. I recommend using fragrant nuts. Toasted hazelnuts are a good substitute for the peanuts.
THE FLAVOR APPROACH
Butter works as the fat of choice here due to its higher smoke point. As the butter melts, it separates into its constituents—fat, water, sugars, and milk solids—which undergo caramelization and the Maillard reaction.
The sugars concentrate as the water evaporates during cooking. Fish sauce adds a spot of umami to the sauce, you can use vegan fish sauce as an alternative. The peanuts and scallions provide crunch against the softer textures of the potato and the dressing.
To prepare the sweet potatoes, preheat the oven to 400°F [204°C].
Rinse and scrub the sweet potatoes under running tap water. Slice them lengthwise and place them in a roasting pan, cut side facing up. Brush with the butter and season with salt. Cover the pan with a sheet of aluminum foil and press around the edges to seal snugly. Bake for 20 minutes. After 20 minutes, remove the foil, flip the sweet potatoes, and cook, uncovered, for 20 minutes more, until the sweet potatoes are cooked thoroughly and are tender; a knife inserted into the center of the sweet potato should slide through easily. Remove from the heat and let rest for 5 minutes.
To prepare the dressing, in a small bowl, combine the crème fraîche, maple syrup, lime juice, fish sauce, if using, and pepper. Taste and season with salt.
To serve, top the warm roasted potatoes with a few tablespoons of the maple crème fraîche dressing. Sprinkle with the scallions, peanuts, red chilli flakes, and lime zest. Serve with the extra dressing on the side.