While the meatballs are cooking, in a small pot add the beef stock, gochujang, cider vinegar, and honey. Bring to a boil.
In a small bowl, combine the cornstarch and the soy sauce and whisk together until combined. Add the cornstarch mixture into the boiling beef stock and whisk vigorously to combine. Bring back to a boil and then remove from the heat. The sauce should be thick enough to coat the meatball.
Add in the toasted sesame seeds.
Toss the cooked meatballs and the sauce in a bowl. Serve on plates with the sliced scallions on top and more sesame seeds.