In a bowl mix together turkey, egg, milk, garlic, cracker crumbs, mozza cheese, onion, ginger powder, 1-2 tablespoons Dijon mustard (if using) seasoning salt and black pepper.
Shape into about 30 meatballs (1-inch each).
Place onto prepared baking dish.
Bake uncovered for 20-25 minutes, or until juices run clear.
In a saucepan combine pineapple juice, garlic, green pepper, honey, onion powder and cornstarch; mix to combine and bring to a boil, whisking/stirring constantly.
Cook and stir for 2 minutes; reduce heat. Add/whisk in 3 tablespoons mustard until smooth.
Remove the cooked turkey meatballs from the oven and brush with about 1/2 cup sauce (or more) and return the meatballs to the oven, and cook for another 10 minutes.