Cut the chicken breast into small pieces.
Remove excess water from the tofu and slice it into 1cm-thick pieces.
Finely chop the onion and bell pepper.
Heat olive oil in a pan and stir-fry the chicken breast.
Add the chopped onion and bell pepper, and stir-fry together.
Season with salt and pepper.
Place the tofu slices at the bottom of an oven-safe dish and top with the stir-fried mixture.
Evenly pour tomato sauce over the top.
Sprinkle with mozzarella cheese.
Bake in a preheated oven at 180°C (356°F) for 15 minutes until done.