Combine the ground beef, onion soup mix, bread crumbs and milk in a large bowl. Mix them together with your hands and form 8 patties.
Heat the oil in a skillet. Roll the patties in the flour and brown them in the hot skillet. Brown both sides, then move them to the slow cooker. You can stack them as needed to get all 8 in there.
Mix the remaining ingredients in a bowl and pour over the meat. Cook on low for 5 hours.