In a large bowl, combine the ground beef, breadcrumbs, beaten egg, minced garlic, grated ginger, and soy sauce. Mix gently with your hands until just combined.

Scoop out a small portion of the meat mixture and roll it between your palms to form bite-sized meatballs, about 1 inch in diameter.

Heat vegetable oil in a large skillet over medium heat. Add the meatballs in a single layer, and cook for about 8-10 minutes, turning occasionally until browned and cooked through.

In the same skillet, reduce heat to low and add the sauce made from soy sauce, brown sugar, gochujang, rice vinegar, an additional minced garlic clove, and sesame oil. Whisk until combined and simmer for 3-4 minutes.

Return the browned meatballs to the skillet and toss in the thickened sauce. Cook for an additional 2-3 minutes to coat the meatballs evenly.

To serve, spoon warm cooked rice into bowls, top with glazed meatballs, garnish with cucumber, carrots, and green onions, and sprinkle with sesame seeds.