Cut the tofu into 1cm thick slices.
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 grill until golden brown.
Pour tomato sauce over the grilled tofu.
Top with mozzarella cheese.
Bake in a preheated oven at 180°C for 10 minutes to finish.