Chop the onion and bell pepper.
Slice the mushrooms.
Heat olive oil in a pan, then sauté the onion, bell pepper, and mushrooms.
Scoop in the soft tofu with a spoon, add a pinch of salt, and mix well.
Pour in the tomato sauce and blend all the ingredients evenly.
Transfer to a gratin dish and top with mozzarella cheese.
Bake in an oven or air fryer at 200°C for 10 minutes.
Finish by sprinkling with parsley flakes.