Dredge both sides of steak in flour and season with salt and pepper.
Heat skillet over medium-high heat and brown meat. Brown in batches to be sure not to over load the skillet. Place browned steaks in casserole dish.
Add onions and mushrooms to skillet, scraping browned bits from bottom. Reduce heat to low, cover, and cook until vegetables are softened, approximately 5 minutes.
Add remaining ingredients and stir to combine.
Pour over steaks in casserole dish.
Cover and bake in preheated oven for 1 hour.
Serve over noodles or rice.