In a large bowl, mix together the ground beef, onion soup mix, bread crumbs, and milk using your hands. Shape into 8 patties.
Heat the oil in a large skillet over medium-high heat. Dredge the patties in flour just to coat, and quickly brown on both sides in the hot skillet. Stack browned patties in the slow cooker. In a medium bowl, mix together the cream of mushroom soup, au jus mix, and water. Pour over the meat. Cook on the Low setting for 4 or 5 hours, until well done.