Make the popular Vietnamese-style sandwich at home with fork-tender pot roast and quick pickled toppings.
Combine carrots and radishes in large bowl; set aside. Heat rice vinegar and 1/4 cup brown sugar in small saucepan over medium heat 1 to 3 minutes or until sugar dissolves, stirring occasionally. Pour over vegetables. Cover and refrigerate until ready to serve.
Preheat oven to 325°F. Combine beef Cross Rib Roast, 1-1/2 cups water, remaining 1 tablespoon brown sugar, fish sauce, garlic and ginger in stockpot over medium heat stirring constantly until sugar dissolves; bring to a boil. Reduce heat; cover tightly. Continue cooking in 325°F oven 1-3/4 to 2-1/4 hours or until beef is fork-tender.
Remove beef; keep warm. Skim fat from cooking liquid. Measure 1-1/4 cups cooking liquid; discard remaining liquid. Return reserved cooking liquid to stockpot. Dissolve cornstarch in remaining 1 tablespoon water; stir into cooking liquid. Bring to a boil; cook 1 to 2 minutes or until sauce is thickened, stirring occasionally. Return beef to cooking liquid; cook additional 1 to 2 minutes or until heated through, stirring occasionally.
Strain vegetables from rice vinegar mixture; discard liquid. Slightly hollow out centers of split rolls. Spread 1 tablespoon mayonnaise on top and bottoms of each roll. Evenly fill each roll with beef and vegetables. Garnish with toppings, as desired.
Test Kitchen Tips Avoid lifting the lid of your cooking vessel, which releases valuable heat and moisture and can significantly increase the cooking time.