Chop the onion and bell pepper (if using). Rinse and drain the kidney beans.

Brown the ground beef with the chopped onion in a skillet for 5-7 minutes, or add raw beef directly to the crockpot.

Transfer the beef and onions (or raw beef) into the crockpot. Add kidney beans, diced tomatoes with juice, and chili seasoning.

Cover the crockpot and cook on low for 6-8 hours or on high for 3-4 hours.

Stir well before serving and garnish as desired.