1. Combine the mirin, sugar, soy sauce, chopped garlic, chopped ginger and diced onions in a saucepan and bring to a boil.
2. Reduce the heat and simmer for 5 minutes.
3. Add in the turkey meatballs and Thai sweet chili sauce and return to a boil.
4. Reduce the heat and simmer for 12–15 minutes (until the meatballs have reached an internal temperature of 165℉).
5. In a large pan, heat the sesame oil over medium-high heat for about 2 minutes and add the zucchini noodles. Sauté the noodles for 30–45 seconds, until cooked but firm, then portion into 4 individual pasta bowls or a large dish.
6. Remove the individual meatballs from the saucepan and place them over the zucchini noodles (6 per portion).