1. Preheat oven to 425 degrees F. Line a baking sheet with foil and spray with vegetable cooking spray.
2. Prepare the meatballs. In a large bowl, lightly beat egg whites. Finely mince water chestnuts and scallion and add to eggs. Add ground beef, flaxseeds, sesame seeds, salt, and pepper. Gently mix to combine using your hands or a wooden spoon. Divide mixture into 24 portions and roll each into a ball about 1 inch in diameter. Place on prepared baking sheet. Bake 10 minutes, until firm and almost cooked through.
3. While meatballs bake, prepare the sauce. In a medium saucepan, combine pineapple juice, soy sauce, honey, vinegar, and ginger. Bring to a boil over high heat. Transfer 3 Tbsp. of the hot liquid to a small heat-proof bowl and stir in cornstarch, whisking until smooth. Pour this mixture into the pot, whisking to combine. Whisk constantly until glaze has thickened, 2 to 3 minutes. Remove from heat. Stir in sesame oil. Transfer 1/2 cup of the sauce to a small bowl.
4. Drizzle remaining sauce over meatballs in pan after they've baked 10 minutes, tossing to coat all the meatballs with glaze. Continue baking until meatballs are cooked through, about 5 more minutes. Thinly slice scallion to use for garnish.
5. Transfer meatballs to a serving platter and garnish them with scallion and sesame seeds. Serve with toothpicks on the side, along with remaining teriyaki sauce in a bowl.
Source: Hannaford fresh Magazine, November - December 2014