Ingredients

• 1 1/2 pounds lean ground beef
• 1 yellow onion, chopped
• 1 red bell pepper, chopped
• sea salt and ground black pepper to taste
• 1 1/2 cups ketchup
• 3 tablespoons apple cider vinegar
• 3 tablespoons Worcestershire sauce
• 3 tablespoons brown sugar
• 3 tablespoons yellow mustard
• 3 tablespoons hickory flavored barbecue sauce
• 2 tablespoons grated Parmesan cheese
• 5 large hamburger buns, toasted