Cut the tofu into 2cm thick slices.
Slice the onion, bell pepper, and broccoli into bite-sized pieces.
Heat olive oil in a pan and stir-fry the onion, bell pepper, and broccoli.
Place the tofu in the pan and top it with the sautéed vegetables.
Spread tomato sauce evenly over everything.
Add cheese on top and bake in the oven at 180°C for 15 minutes.
Transfer the completed tofu gratin to a plate.