In a shallow dish, combine grill seasoning, dark soy, a tablespoon honey, 1 teaspoon of the hot pepper flakes, half of the chopped garlic, sesame oil, scallions and a drizzle of vegetable oil. Coat the flank steak in the mixture and let it stand 10 minutes.
Preheat indoor electric grill, stove top grill pan or outdoor grill to medium high. When the grill pan or grill is screaming hot, add meat and cook 5 minutes on each side for medium rare, 7 to 8 minutes on each side for medium well doneness.
Heat a large skillet over high heat. Add 2 tablespoons vegetable oil, cabbage and peppers. Season with salt and stir fry 2 or 3 minutes. Add a drizzle of honey, about 1 tablespoon, hot pepper flakes and garlic and toss to combine with cabbage. Add sauerkraut and mix in, heating it through 1 minute. Turn off heat.
To serve, let meat rest 5 minutes for juices to redistribute. Thinly slice the meat on a heavy angle against the grain (the lines in the meat). Pile the slaw up and top with sliced Korean steak and serve.