Heat oven to 375ºF with rack set in upper-middle position.
Tear 2 slices bread into bite-sized pieces and add to large mixing bowl. Add ½ cup milk and mash together to form a paste.
In a mini food processor or blender, pulse 6 chopped green onions, ½ bunch cilantro, 1 (2-inch) piece ginger and 2 cloves garlic until minced.
Add minced herb mixture, 2 eggs, 1 tablespoon gochujang, 2 teaspoons kosher salt, and 1 teaspoon pepper to bowl with soaked bread; mix to combine. Add 1 ½ pounds ground beef and mix just until combined.
Scoop meat mixture by ¾ cup measure (about 6 ½ ounces) and form into individual oval-shaped loaves about 3 inches wide and 4 inches long. Arrange evenly on sheet pan.
In a small bowl, whisk together 3 tablespoons brown sugar, 3 tablespoons ketchup and 1 tablespoon gochujang; brush evenly over loaves.
Bake until an instant read thermometer inserted in the centers registers 155ºF, about 25 minutes. Turn oven to broil and broil until deeply browned on top, 5–15 minutes, depending on your oven. Rest 5 minutes before serving.