In a 6 quart slow cooker, combine 1 (14 ounce) can jellied cranberry sauce, ½ cup honey, ⅓ cup balsamic vinegar, ⅓ cup low sodium beef broth, 1 tablespoon corn starch, 1 teaspoon minced garlic, ½ teaspoon salt and whisk until smooth.
Stir in 2 pounds precooked beef meatballs until coated in the sauce.
Cover and cook on low for 4-6 hours or high for 2-3 hours, until meatballs are heated through and sauce has thickened. Sprinkle with a pinch of red pepper flakes for garnish , if desired.