Marinate the chicken breast in balsamic vinegar for at least 30 minutes. Preheat oven to 200˚C. In a roasting pan or casserole dish, add the potatoes and onion. Season with salt, pepper and fresh oregano. Heat olive oil in large skillet and brown the chicken on both sides for about 2 minutes on each side. Season with salt and pepper. The chicken will be browned, but not cooked through. It will finish cooking in the oven…