In cast iron skillet or large frying pan, heat oil and cook onion and green pepper over medium-high heat until onion is translucent and green pepper softens, about 5 minutes.
Add garlic. Cook 1 minute. Place contents from skillet into large bowl and set aside.
Cook beef until no pink remains. Drain.
Add onion, pepper and garlic back to skillet. Add ketchup, Worcestershire sauce, brown sugar, salt and pepper. Mix well.
Add water. Keep cooking over medium-high heat until mixture just starts to boil, then reduce heat and simmer for 10 minutes, stirring occasionally.
Toast hamburger buns. Scoop Sloppy Joes mixture onto bun. Eat as closed or open sandwich.