Cut the tofu into bite-sized pieces.
Chop the tomato finely.
Slice the onion and bell pepper into strips.
Heat olive oil in a pan and sauté the onion and bell pepper.
Add the tofu and tomato to the pan and stir-fry together.
Season with salt and pepper.
Top with mozzarella cheese, cover, and cook until the cheese melts.
Transfer to a plate and sprinkle with basil.