Trim the fat from beef roast and cut into 4 or 5 large chunks to fit into a crock pot.
Season all sides of the beef chunks and then dredge in the flour. In a skillet, melt the butter and then brown the meat slowly on all sides and then place meat in the crock pot.
Brown the onion and garlic in the pan. Deglaze the browning pan with the wine. Combine the remaining ingredients and simmer for a few minutes
Pour this mixture over the beef. Cover and cook on HIGH for 4 hours and then cook on LOW for 4 hours, until very tender.
Remove the meat from the crock pot. Pour the juice into a small saucepan, bring to a boil and then simmer on the stove for 15 to 20 minutes to reduce and thicken. In the meantime shred the beef with 2 forks and return to the crock pot.
Return the thickened sauce to the beef in the slow cooker and stir through. Taste and adjust the seasonings as needed.
Keep warm and serve on split sandwich buns.
Makes 12 to 16 sandwiches.