Chop the green pepper and onion, place both in a large pot.
Add the ground beef to the pot and cook over medium-high heat until beef is no longer pink, and green pepper is softened, and onion is translucent. Drain the fat.
Add about 1/4 cup each tomato sauce and ketchup to beef mixture and stir well. Taste to see if if it needs more tomato sauce and/or ketchup. The taste should be a balance of the two, and the mixture should not be dry. The liquid will absorb. I generally use at least half the can of tomato sauce and about the same amount of ketchup. It's a taste as you go type of recipe.
Put the mixture back on about medium heat and let the sauce heat through. Turn heat to low, cover and serve on sandwich rolls.