Cut the tofu into bite-sized pieces.
Finely chop the onion and bell pepper.
Add olive oil to a pan and sauté the onion and bell pepper.
Add the tofu to the pan and lightly sauté.
Pour in the tomato sauce and mix well.
Place the tofu, vegetables, and sauce in an oven-safe dish.
Sprinkle mozzarella cheese on top.
Bake in a 180°C oven for 15 minutes.