In a large skillet add oil & lightly brown round steak,drain. Next brown Italian sausage until cooked and crumbly.
Place browned round steak & sausage in a 5 qt. slow cooker. Layer onions, bell pepper strips & mushrooms over meat. Add salt & pepper to taste. Pour spaghetti sauce over all. Cover & cook on low for 8 hours or until meat is tender. Serve over thick slices of fresh Italian or french bread.