Preheat oven to 450°F (230°C). Line a standard-size baking sheet with parchment paper or a baking mat, and set aside.
In a large mixing bowl, combine the milk and panko breadcrumbs. Allow to soak for 5 minutes. Add the chicken, egg, garlic, green onion, soy sauce, ginger, salt, and pepper. Using your hands, mix together just until combined (overworking it will cause the meatballs to be dense).
Shape into meatballs and place onto the prepared baking sheet. Place in the oven and bake for about 15 minutes or until cooked throughout (internal temperature of 165°F/74°C).
Meanwhile, in a small saucepan set over medium-low heat, combine the chicken broth, orange juice, orange zest, sugar or honey, vinegar, soy sauce, garlic, ginger, black pepper, and red pepper flakes. Bring the mixture to a low simmer. In a small bowl, whisk together the cold water and cornstarch, and add to the saucepan. Whisk until combined, and continue cooking for 5 minutes or until the sauce thickens (I usually let mine go for about 8 minutes).
Place the meatballs in a large bowl and cover with sauce. Toss to coat, and serve hot.
Video
Notes
-You can also use ground pork for these, too!To STORE Orange Chicken Meatballs, place them in an airtight container and refrigerate for up to 4 days. FREEZE in a single layer on a baking sheet, then transfer to a freezer bag for up to 3 months.REHEAT in the microwave or in the oven at 350°F (175°C) until heated through. For the best texture, reheat in the oven after thawing in the fridge overnight.