Preheat the oven to 375 degrees and line a baking sheet with parchment paper.
In a large bowl, combine the ground beef, panko breadcrumbs, egg, onion, garlic, 2 tablespoons gochujang, 1 tablespoon grated ginger, and 1 tablespoon soy sauce. Mix until evenly blended but do not overwork the meat.
Shape the mixture into a loaf about 8 inches long and place it on the prepared baking sheet.
Bake for 30 minutes. While it bakes, stir together the remaining 1 tablespoon gochujang, honey, rice vinegar, and remaining 1 tablespoon soy sauce to make the glaze.
Remove the meatloaf from the oven and brush the glaze evenly over the top and sides. Return it to the oven and bake for another 20 minutes until the internal temperature reaches 160 degrees.
Let the meatloaf rest for 10 minutes before slicing. Sprinkle with sesame seeds and sliced green onions just before serving.