Cut the tofu into bite-sized pieces.
Finely chop the onion and bell pepper.
Heat olive oil in a pan and sauté the onion and bell pepper.
Add the tofu and stir-fry briefly.
Season with salt and pepper.
Place the sautéed ingredients in an oven-safe dish and add tomato sauce on top.
Top with mozzarella cheese.
Bake in a preheated oven at 200°C for 10 minutes.