Place the cutlets between two pieces of plastic wrap and pound the cutlets to 1/4-inch thick. Transfer to a plate and season each cutlet with salt and pepper.
Dredge each cutlet in the flour and shake off the excess.
Put a large saute pan over a medium-high flame and heat 2 tablespoons of the oil until shimmering. Cook the cutlets in batches searing them for about 1 minute on each side, do not overcook. Transfer to a plate.
In the same pan add the remaining oil. Add the onions and saute until soft, about 5 minutes. Add the garlic and mushrooms and peppers, wine and broth. Cook until soft, about 4-5 minutes. Add in the butter and return the cutlets to the pan. Cook for 2-3 minutes and serve immediately with crusty bread.