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. Serve hot cooking liquid as a dipping sauce. Yield: 9 servings (serving size: 3 ozs. beef and 1 bun). Nutritional value: Calories 324 (26% from fat), protein 32.2g, Fat 9.4g (Sat 3.5g, Mono 4. 1g, Poly 0.8g), Carb 24.5g, Fiber 1.2g, Chol 81mg, iron 4.3mg, Sodium 435mg, calcium 31mg beef 24