Sloppy Joes

Name: Sloppy Joes
Prep time: 10 min
Cook time: 20 min
Total time: 30 min
Cuisine: American
Ingredients: 2 tbsp. butter, plus more for buttering rolls; 2 1/2 lb. ground beef; 1/2 large onion, diced; 1 large green bell pepper, diced; 5 garlic cloves, minced; 1 1/2 c. ketchup; 2 tbsp. brown sugar; 2 tsp. chili powder, plus more to taste; 1 tsp. dry mustard; 1/2 tsp. red pepper flakes, plus more to taste; 1 c. water; Kosher salt, to taste; Freshly ground black pepper, to taste; 2 tbsp. tomato paste (optional); Worcestershire sauce, to taste; Tabasco sauce, to taste (optional); 8 Kaiser rolls; Kettle cooked potato chips, for serving