Preheat the oven to 425°F (220°C). Line a rimmed baking sheet with parchment paper or foil.
In a large bowl, combine ground beef, crushed crackers, half of the sliced scallions, egg, minced garlic, 2 tablespoons gochujang, 2 tablespoons soy sauce, minced ginger, 1/2 tablespoon sesame oil, black pepper, and red chili flakes; mix gently with your hands until just combined.
Portion the mixture into 2-ounce (about 2-inch) meatballs and arrange them on the prepared baking sheet; you should have about 12 meatballs.
Bake the meatballs until browned and an instant-read thermometer inserted into the center reads 165°F (74°C), about 15–20 minutes.
While the meatballs bake, make the glaze: in a small saucepan over medium heat, combine apricot preserves, 2 tablespoons gochujang, 1 1/2 tablespoons rice vinegar, and 1 tablespoon soy sauce; warm and stir until the mixture is heated through and slightly thickened, about 5 minutes.
Brush the warm glaze over the baked meatballs to coat them evenly.
Sprinkle with remaining thinly sliced scallions and sesame seeds, and serve with cooked rice if desired.