Cut vegetables such as onion, bell pepper, and potato into bite-size pieces.
Slightly boil the potatoes to prepare them.
Heat olive oil in a pan and sauté the onions, bell pepper, and potatoes.
Season with salt and pepper.
Transfer the sautéed ingredients to an oven-safe dish and top with tomato sauce.
Add mozzarella cheese and parsley on top.
Bake in a preheated oven at 180°C for 10-15 minutes.