Press tofu for 30 minutes. Cut into ½-inch thick slices, then quarter each slice.
Pour barbecue sauce into an 8-inch square baking dish. Place tofu in dish and gently toss to coat. Let tofu marinate in sauce for 1 hour (or more), turning occasionally.
Preheat oven to 400 degrees. Spray a rimmed baking sheet with oil or cooking spray. Place tofu on baking sheet (do not discard barbecue sauce!) and bake for 20 minutes. After 20 minutes, turn tofu over and brush with additional barbecue sauce. Bake 20 minutes more or until tofu is browned on edges. Toss tofu in remaining barbecue sauce and serve.