Cut tofu into bite-sized pieces.
Finely chop onion and bell pepper.
Heat olive oil in a pan and sauté onion and bell pepper.
Add tofu and stir-fry briefly.
Season with salt and pepper.
Place the sautéed ingredients in a heat-resistant dish and pour tomato sauce over them.
Sprinkle mozzarella cheese on top.
Bake in a 200°C oven for 10-15 minutes.