In a large mixing bowl, combine the ground meats, breadcrumbs, and egg. Mix well to combine, but don't over-mix, as the meat can get tough!
Cover the bowl with plastic wrap and set in the fridge for at least 30 minutes.
While the meat is in the fridge, preheat the oven to 425°F. Once the meat has chilled for long enough, roll the meat into 1" meatballs, then place them on a greased baking sheet.
Bake for 20 minutes, or until the surface is golden brown and the meat cooked through, 165°F minimum.
Remove from the oven. In a separate bowl, combine all the ingredients for the bulgogi sauce and mix until the sugar dissolves.
Toss the meatballs in bulgogi, then serve over rice and enjoy!
Notes
Be careful not to over-mix the meat. Over-mixing can break up the muscle fibers too much, leading to the meat getting dense and tough. Remember to only mix the meat for a maximum of 45 seconds!
Panko bread crumbs are different than regular breadcrumbs! It has a fluffier, larger grain that results in softer and more tender meatballs. Alternatively, you can use milk and bread: just soak 2 slices of white bread in milk, then squeeze the milk out and mash the bread up into a paste before adding it to the meatball mix.
To make a thicker bulgogi, add 1 Tablespoon of cornstarch to a splash of cold water and stir. Heat the sauce to boiling while stirring frequently, then cool. It will thicken as it cools!
You can use the meatball mixture to make bulgogi burgers! Just flatten the mix into a patty shape, bake or pan-sear them (ALWAYS cook to 165°F if you're using ground pork!), and serve with bulgogi sauce and Asian cabbage coleslaw!