Cut the soft tofu into appropriate-sized pieces.
Finely chop the onion, bell pepper, and mushrooms.
Heat olive oil in a pan and sauté the onion, bell pepper, and mushrooms.
Add tomato sauce to the sautéed vegetables and mix well.
In an oven-safe dish, layer the soft tofu, sautéed vegetables, and sauce evenly.
Top with mozzarella cheese.
Bake in a preheated oven at 200°C (392°F) for 15 minutes.
Garnish with parsley and serve.