Heat oil in large skillet over medium-high heat until hot. Sprinkle steak with salt and pepper. Place steak in skillet; cook 4 to 6 minutes or until well browned, turning once. Transfer steak to 4- to 6-quart crockpot. Top with onion and bell pepper. In same skillet, combine soup and salsa; mix well. Pour over vegetables and steak. Cover; cook on low for 8 to 10 hours. Remove steak pieces from crockpot; place on serving platter. Stir sauce well. Serve sauce with steak.