Mix together ground beef, egg, onion and breadcrumbs. Form mixture into meatballs about 1 to 1.5 inches in size. Put meatballs on a baking sheet lined with parchment and freeze until solid. When solid put meatballs into a gallon sized freezer bag. Mix together rice vinegar, ketchup, brown sugar, pineapple and juice, and gf soy sauce. Put mixture into a second gallon sized freezer bag. Put the bell peppers, corn starch and broth into a quart sized freezer bag. Remove as much air as possible from each bag, seal, bundle one of each type of bag together, label and freeze.