Ingredients:

  Amount  Measure       Ingredient -- Preparation Method
--------  ------------  --------------------------------
   3 1/4  pounds        lean boneless chuck roast
     1/3  cup           white vinegar
     1/2  teaspoon      salt
     1/4  teaspoon      ground cloves
     1/8  teaspoon      garlic powder
   1      large         onion -- cut into 8 wedges
   3                    bay leaves
   9                    hamburger buns -- (1-1/2-ounce)  split
   9                    lettuce leaves

Preparation:

Trim fat from roast. Place roast and next 6 ingredients in a slow cooker. Cover and cook over low heat for 11 hours or until roast is tender. Remove roast from slow cooker; let stand 10 minutes. Separate roast into bite-size pieces, and shred meat with 2 forks; set aside. Strain cooking liquid; discard solids. Cover and freeze at least 1 hour. Skim fat from surface of cooking liquid; discard. Place cooking liquid in a saucepan, and bring to a boil; remove from heat. Line bottom halves of buns with a lettuce leaf; top each with shredded beef and top half of bun.