Prep Your Oven: Start by preheating your oven to 400°F (200°C). Line a large baking sheet with parchment paper – this makes cleanup a breeze and prevents sticking.
Gentle Mix: In a spacious mixing bowl, combine the ground beef, ground pork, whole egg, egg yolk, minced garlic, panko bread crumbs, the first 3 tablespoons of teriyaki sauce, diced water chestnuts, sliced green onions, and black pepper. Mix everything together gently until just combined. Overmixing can make meatballs tough, so a light touch is key!
Form the Meatballs: Roll the mixture into uniform 1 to 1 ½ inch balls. Using a cookie scoop can help you create consistently sized meatballs, ensuring they cook evenly. Place them in a single layer on your prepared baking sheet.
Bake to Perfection: Bake for approximately 20 minutes, or until the meatballs are thoroughly cooked through and lightly browned. Once done, let them rest on the baking sheet for 5 to 10 minutes.
Glaze and Garnish: Transfer the warm, baked meatballs to a clean bowl. Pour the remaining ½ cup of teriyaki sauce over them and toss gently until each meatball is coated in the delicious glaze. For an extra touch, sprinkle with additional thinly sliced green onions and sesame seeds.
Serve & Enjoy: These delightful teriyaki meatballs are ready to serve immediately! Enjoy them as a crowd-pleasing appetizer with toothpicks, or serve over rice for a simple, satisfying, and healthy weeknight dinner.