Preheat the oven to 350°.
Add the ground beef, graham cracker crumbs, onion, onion soup mix, pepper, egg, and evaporated milk to a large bowl. Work the ingredients together until well combined, then form the mixture into balls.
While the meatballs are cooking, combine the pineapple chunks, green pepper, brown sugar, cornstarch, vinegar, and soy sauce in a large resealable freezer bag.
Remove excess air from the bag and seal.
Freeze.
Thaw.
Preheat the oven to 350°. Pour the contents of the bag into a baking dish and cover. Bake for one hour.
Thaw.
Pour the contents of the bag into the crockpot. Cook on low for 4 to 5 hours or high for 2 to 3 hours.