Wash the peppers and remove the insides. In 2/5 cup (100 ml) of oil, fry the chopped onions, then add the washed rice, 2-3 finely chopped tomatoes and the mushrooms. Stir well and after they fry, add 1 cup of warm water. Season with salt and black pepper and allow the rice to absorb the liquid. Stuff the peppers with the filling and dip the openings in flour.
Arrange them in a greased tray. Separately, heat 4-5 tablespoons of oil and fry the remaining 3-4 grated tomatoes. Dilute the roux with 1 cup of hot water. Fill the peppers with the roux and put them to roast until tender in a preheated 356°F (180 °C) oven and flip them over once during roasting.
Serve the stuffed peppers with rice and mushrooms with some crushed parsley.