Combine 1 1/2 pounds chopped peeled sweet potatoes, 1 bunch scallions (cut into 2-inch pieces), 6 crushed garlic cloves and 1 tablespoon fresh thyme in a bowl. Drizzle with 1/4 cup olive oil, season with salt and pepper and toss. Place on a sheet of foil and fold up. Grill over low heat until the potatoes are tender, 20 to 25 minutes.
Photograph by Kang Kim