Preheat the oven to 450° and brush a rimmed baking sheet covered with foil and spray with cooking spray. In a large bowl, mix together the rest of the ingredients except for the sweet and sour sauce and red pepper flakes. Form the mixture into 1 1/2 -inch balls and arrange on the baking sheet. Bake for about 13 minutes, until browned and cooked through. Transfer the meatballs to a platter and serve with Spicy Sweet and Sour sauce. (Mix some crushed red pepper into the Sweet and Sour sauce until spicy. Then sprinkle some on top to let guests know that sauce is spicy.) Recipe inspired from Food & Wine.