Cut the tofu into bite-sized pieces.
Finely chop vegetables such as onion and bell pepper.
Heat olive oil in a pan and sauté the vegetables.
Add tofu and salt, and gently stir-fry.
Place the tofu and vegetables into a gratin dish.
Evenly pour tomato sauce over the top.
Top with mozzarella cheese.
Bake in the oven at 200°C for 15 minutes.