Brown ground beef in a large skillet over medium heat.

Add chopped green bell pepper and chopped onion to the skillet and cook until softened.

Drain any excess grease from the skillet.

Return the meat mixture to the skillet.

Add ketchup, water, beef bouillon granules, sugar, and prepared mustard to the skillet.

Stir well to combine all ingredients.

Bring the mixture to a boil.

Reduce heat to low, cover the skillet, and simmer for 15-20 minutes, stirring occasionally.

Serve the Sloppy Joe mixture on warm, toasted hamburger buns.