Pour the frozen meatballs into the basin of a 6 quart slow cooker.
In a medium bowl, add the honey, soy sauce, ketchup, oil, garlic, onion and red pepper flakes. Stir well to combine. Pour the sauce over the meatballs.
Cover and cook on HIGH for 2.5-3 hours or LOW for 4-6 hours.
Stir and serve. Garnish with sliced green onions, if desired.
Use any fully cooked frozen meatball you like - beef, chicken, turkey, pork, veggie/plant based.If you want to thicken the sauce, to a small bowl, whisk together 2 Tablespoons cold water with 1 Tablespoon cornstarch. Once whisked, spoon in a bit of the sauce from the slow cooker, mix, and then pour back in & stir to thicken.