Crock Pot BBQ Meatball Sandwiches

I made these one Saturday when we had a night football game that we wanted to watch on TV. It was perfect because at dinner time I just had to throw these sandwiches together quickly. The BBQ sauce has this tangy aspect too it that was different but really enjoyable. These were a hit and would make a great busy weeknight dinner too! Recipe is adapted from Amanda's Cookin.

Meatballs:
1/2 cup breadcrumbs
1 tsp onion powder
2 tsp chili powder
1/2 tsp cumin
1 tsp salt
1/2 tsp black pepper
1 egg
1 tbsp olive oil
1 lb ground beef

Sauce:
2 cups ketchup
1/4 cup apple cider vinegar
2 tbsp worcestershire sauce
2 tbsp brown sugar
1 tbsp chili powder
1 tbsp grlic powder

4-6 Rolls
4-6 slice provolone cheese

In a large bowl combine the breadcrumbs, onion powder, chili powder, cumin, salt and black pepper. Add the ground beef, egg and olive oil and combine. Using your hands, form meatballs and place in the bottom of the crock pot. In a bowl whisk together all of the ingredients for the sauce. Spoon the sauce over each meatball and pour over the remaining sauce. Cook on low for 7-8 hours.  Once the meatballs are done, split the rolls and lightly toast. Top with meatballs and cheese.