Portobello Mushroom Sautee (Sotelenmiş Portobello Mantar)

2 large Portobello mushrooms (sliced)
2 green bell peppers (sliced)
1 red onion (sliced)
1 tbsp olive oil
Salt and ground black pepper

Heat olive oil in a large pan. Add the mushrooms and sautee for 3-4 minutes. Add peppers and sautee 2 more minutes. Finally, add the onions along with salt and pepper. Serve as a side dish or a main dish if you prefer.