In a bowl, mix together ground beef, soda cracker crumbs, onions, egg, salt, ginger and milk. Shape a tablespoon each into rounded balls.
Melt shortening in a skillet over medium heat. Cook meatballs, working in batches if your skillet isn't big enough. Remove meatballs from skillet and pour away leftover fat.
In the same skillet, mix together cornstarch and sugar. Stir in reserved pineapple syrup, vinegar and soy sauce. Cook over medium heat, stirring constantly, until mixture thickens and boils.
Add meatballs, pineapple tidbits and green pepper to skillet. Heat for 3 to 5 minutes. Serve hot.