Diet Coke Sloppy Joes

Ingredients

• 1 pound raw extra lean ground beef
• 1 medium onion(s)
• 1 1/2 Tbsp all-purpose flour
• 1 cup Coca-Cola Diet Coke
• 2/3 cup ketchup
• 2 Tbsp vinegar
• 1 Tbsp Worcestershire sauce
• 2 tsp dry mustard