In a large mixing bowl, knead together ground beef, panko, gochujang, soy sauce, sesame seeds, garlic, ginger, sesame oil, and egg.
Shape the meat into a loaf and put it on a 4 sided baking sheet or 9x13 pan.
Bake for about 45 minutes.
Meanwhile, make the glaze. In a small saucepan over medium-high heat, whisk together the sesame oil and cornstarch. Stir in the soy sauce, rice vinegar, brown sugar, garlic, ginger, and sesame seeds. Bring to a simmer and cook until sauce thickens. Pour or brush half the sauce over the meatloaf about half-way through the cooking time.
Increase the oven temperature to 450 degrees. Pour or brush remaining sauce over the meat and bake an additional 15 minutes.
***You can also substitute with 1/2-1 teaspoon crushed red pepper flakes, the same amount of sriracha sauce, or if you don't want this to be spicy, simply leave it out.