Prepare a baking sheet by lining it with parchment paper or foil. If using foil, lightly grease it to prevent sticking. Extend the parchment slightly over the sides to catch drips and ease cleanup.
In a large bowl, add the ground beef, chopped scallions, diced bell peppers, ginger, garlic, panko crumbs, egg, Gochujang, and salt. Mix gently with your hands just until everything is incorporated—be careful not to overmix to avoid dense meatballs.
Scoop the meat mixture into even portions, roughly 3 tablespoons each. Using damp hands, roll each scoop into a smooth ball and place them on the prepared sheet pan. Cover loosely with plastic wrap and refrigerate for at least 30 minutes or up to 8 hours. For future use, the meatballs can be frozen at this stage.
Preheat your oven to 425°F (220°C) with the rack set near the top. Bake the meatballs for about 15 minutes, or until cooked through. If using frozen meatballs, increase the baking time by 5–6 minutes.
Remove the meatballs from the oven. Dip each one into the prepared sauce using a fork, coating it generously. Return them to the baking sheet and bake for another 4–5 minutes until the glaze is bubbling and slightly caramelized.
Serve the glazed meatballs in crisp lettuce leaves such as Bibb, Boston, or Romaine. Offer optional garnishes like jasmine rice, shredded red cabbage, cucumber slices, pickled onions, scallions, chopped cashews, sesame seeds, and fresh herbs such as mint, basil, or cilantro for a customizable and colorful spread.