Preheat the oven to 350 degrees F. Season the beef with salt and pepper; coat in flour, shaking off excess. Heat the oil in a large skillet over medium-high heat. Add steaks and brown on both sides. Transfer to casserole. Lower the heat to medium. Add mushrooms, onions and garlic to the skillet and cook until tender, about 4-5 minutes. Add remaining ingredients and bring to a simmer. Pour mixture over steaks. Cover and cook in the oven 90 minutes, or until tender.