Add honey, soy sauce, ketchup, brown sugar, garlic, ginger and red pepper flakes to a large pan over medium-low heat. Gently whisk ingredients together until smooth. Heat through until small bubble start to form around the edge. You want a simmer, not a boil; about 2-3 minutes.
Pour about 2 tablespoons of cornstarch into a bowl and add 2 tablespoons of the simmering mixture. Whisk to combine until smooth. Whisk the cornstarch mixture into the saucepan. Continue to whisk until completely incorporated.
Cook over medium-low heat for several minutes or until thickened. Add the cooked meatballs to the sauce and toss to coat. Continue to stir over medium-low heat until meatballs are heated through and completely coated with the sauce.
As an appetizer, serve immediately, or transfer to a slow cooker to keep warm. Or serve as a main dish with rice or pasta. Garnish with sliced green onions and sesame seeds before serving if desired.
Store in a tightly sealed container for several days in the refrigerator.
*Slow Cooker version: Add frozen (or cooked) meatballs to the slow cooker. Whisk remaining ingredients (except cornstarch) in a bowl and pour over the meatballs. Cook on low for about 3 hours. To thicken, add 2 tablespoons of the sauce from the slow cooker to a small bowl and whisk in 2 tablespoons of cornstarch until completely smooth. Pour into the slow cooker and stir to combine. Cover and cook on low for an additional 30 minutes to thicken.
This recipe will serve 8 people as an appetizer (5 meatballs per person) and 6 people as a main course (6-7 meatballs per person).Nutritional information is for appetizer servings.