Preheat oven to 400°F (200°C). Line a baking sheet with parchment paper.
In a large bowl, combine ground pork, ground beef, panko breadcrumbs, 2 tablespoons soy sauce, 1 tablespoon sesame oil, minced garlic, grated ginger, and the lightly beaten egg. Mix gently until just combined.
Roll the mixture into 1-inch meatballs. Place on the prepared baking sheet.
Bake for 18-20 minutes, or until browned and cooked through.
While the meatballs are baking, prepare the sauce. In a medium saucepan, whisk together 0.5 cup soy sauce, brown sugar, rice vinegar, hoisin sauce, 1 tablespoon sesame oil, and minced garlic.
In a small bowl, whisk together cornstarch and 2 tablespoons water to create a slurry.
Bring the sauce mixture to a simmer over medium heat. Stir in the cornstarch slurry and cook, stirring, until the sauce thickens, about 2-3 minutes.
Add the baked meatballs to the thickened sauce and toss to coat.
Garnish with sesame seeds and sliced green onions before serving.
Notes
These meatballs are fantastic served with steamed rice or as a crowd-pleasing appetizer.