5 pounds chuck roast
Two 12-ounce bottles Dr Pepper, divided
1/2 cup Chili Smoked Brown Sugar
4 tablespoons (1/2 stick) unsalted butter
1 large yellow onion, chopped
4 cloves garlic, chopped
1 cup ketchup
3 tablespoons tomato paste
1/2 cup cider vinegar
1/3 cup Worcestershire sauce
1/2 cup packed dark brown sugar
1 teaspoon New Mexican chili powder
1 teaspoon black pepper
1 teaspoon kosher salt
3 ancho chilies
3 arbol chilies
6 buns
18 hamburger dills
1/4 red onion, sliced