In a small skillet, cook beef over medium heat until no longer pink; crumble beef. Drain beef and set aside; discard drippings.
In the same skillet, saute the onion, celery, green pepper and garlic in butter until vegetables are crisp-tender, about 5 minutes.
Drain pineapple, reserving juice; set pineapple aside.
Add enough water to the juice to measure ½ cup.
In a bowl, combine the brown sugar, flour, vinegar, salt and pineapple juice mixture until smooth.
Add to skillet. Bring to a boil. Cook and stir over medium heat for 2 minutes.
Stir in beef and pineapple; heat through. Serve with rice.
