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 to the pan and lightly cook it.
Pour in the tomato sauce and mix well with the other ingredients.
Transfer to a gratin dish and top with cheese.
Bake in the oven at 200°C for 10 minutes.