Place flour, salt and pepper into a resealable plastic bag. Add steaks a couple at a time and shake until completely coated. In a skillet, cook steaks in oil until lightly browned on each side. Transfer to a slow cooker.
Add the onion and 2 cups water. Cover and cook on low for 8 hours or until meat is tender. At the end of the 8 hours -- In a bowl, whisk together the gravy mixes with the remaining cup of water. Add to slow cooker; cook 30 minutes more.