To soften a sheet of rice paper, submerge it in a shallow dish of water for five seconds. Transfer to a plate. Working quickly, arrange the lettuce, bell pepper, carrot, cabbage, and tofu in the bottom third of the wrap, leaving a margin on either side. Fold the bottom over the filling, then fold the sides toward the center. Tightly roll the rice paper toward the top until it is completely wrapped. Transfer to a separate plate and repeat this process until all ingredients are used up.