In a large skillet, heat a splash of sesame oil over medium heat. Add the lean ground beef, breaking it into smaller pieces as it cooks for 6–7 minutes. Stir occasionally until the meat is fully browned and no longer pink, then drain any excess fat.

Next, add 1 diced onion, 2 minced garlic cloves, and 1 tablespoon of freshly grated ginger to the skillet. Stir constantly and cook for about 2 minutes, until softened and fragrant.

Pour in 3 tablespoons of soy sauce, 2 tablespoons of brown sugar, and 1 tablespoon of gochujang into the skillet. Stir everything together and let it simmer for 5 minutes.

While the beef mixture is simmering, butter the insides of your hamburger or brioche buns. Toast them over medium heat for 2–3 minutes, until they’re golden brown and slightly crispy.

Spoon the savory beef mixture generously onto the bottom half of each toasted bun. Feel free to add your favorite toppings.

Close the sandwiches with the top halves of the buns and serve immediately.