Prepare the noodles according to package instructions. Drain, rinse under cold water and set aside.
In a small bowl, whisk together the Korean chili pepper flakes, sugar, soy sauce, oyster sauce, mirin and dark soy sauce.
Heat the peanut oil in a large wok or skillet over medium-high heat. Add the ground beef and spread it out in the pan. Let it cook without touching it for at least 5 minutes or until all the meat juice has evaporated and there's a char on the bottom. Using a spatula flip the charred beef and toss it around.
Add the onion, the white parts of the green onion, the garlic and ginger. Cook for another minute or 2 until fragrant.
Add the noodles to the wok and stir everything together. Pour in the sauce and toss everything together so that everything is coated in the sauce. Stir-fry for another 2 minutes. Turn off the heat and drizzle the sesame oil and give it another stir. Serve hot.
