BBQ beef sandwiches

Again, I remind anyone reading this to remember my family size. Most recipes I post, can be divided for smaller (normal) sized families.

3/4 cup dark brown sugar
4 (1-pound) flank steaks (I actually use cheap cuts of roast beef)
2 medium onions, chopped
2 cups tomato paste
1/3 cup Worcestershire sauce
1/3 cup molasses
1/3 cup cider vinegar
2 tablespoons chili powder
2 teaspoons garlic powder
2 teaspoons dry mustard
2 teaspoons ground cumin

I put the roasts in the crock for 1 full day, until they're falling apart, first. Mix all other ingredients together and after pulling the meat apart and discarding the fat, pour over the meat in the crock again (or a new crock if you're like me and have several). Cook 2-3ish hours on high. Serve with rolls and fixings.