In a medium mixing bowl, whisk together the hoisin sauce, soy sauce, rice vinegar, sesame oil, honey, grated ginger, minced garlic, and sriracha until the glaze is emulsified.
Place the frozen meatballs into the basin of a 4-to-6 quart slow cooker.
Pour the sauce mixture over the meatballs and stir with a spatula to ensure each meatball is thoroughly coated.
Secure the lid on the slow cooker and set to high for 2 hours or low for 4 hours.
Stir the meatballs halfway through the cooking duration to redistribute the sauce and prevent sticking.
Once the cooking time is complete, stir once more to coat the meatballs in the thickened glaze.
Garnish with sliced green onions and toasted sesame seeds before serving.