Chop the onion, quarter the mushrooms and cut the peppers into strips. Sauté the onion in heated oil, add the mushrooms, paprika strips and oregano and sauté briefly while stirring. Add the peas and tomatoes, season with salt, pepper and stew for about 5 minutes. Mix the vegetables and macaroni, place in a casserole dish (24 x 28 cm) and sprinkle with cheese. Bake in a preheated oven at 200 degrees (gas: level 3) for about 25 minutes.