1. Place a frying pan on medium heat, and pour olive oil in it.
2. Drop onion in hot oil, and cook for about 4 minutes.
3. Throw mushrooms, and saute well.
4. Add black pepper, chili flakes, and oregano. Cook until nice and tender.
5. Put garlic in pan, stir, and cook for 2 more minutes.
6. Pour wine, and deglaze the pan.
7. Drop balsamic vinegar, fresh basil, and parsley. Mix well. Let the liquid evaporate.
8. Throw butter and stir to combine.
9. Serve mushroom on top of your steak or as a side with a choice of main dish.