Cut meat into large chunks, place the chuck roast pieces into a 4 quart slow cooker. Sprinkle the onion soup mix and brown gravy mix over the roast. Pour the red wine vinegar over the top.

Cover and cook on low for 6 to 8 hours or on high for 4 hours until it is tender enough to shred with two forks. Shred into large or small shreds.

To assemble and serve traditionally: On a plate, place a piece of cooked and crisped garlic toast. Add a layer of mashed potatoes on the toast and top with the beef and some of the au jus sauce out of the crockpot.