In a mixing bowl, whisk together 80 ml of low-sodium light soy sauce, ½ tablespoon of gochujang, 1 tablespoon of mirin, 2 teaspoons of minced ginger, and ½ teaspoon of garlic powder or paste. Add 1 tablespoon of sesame oil and 4 tablespoons of light brown sugar, stirring until the sugar is fully dissolved.

Take 750 g of thinly sliced flank or skirt steak and immerse it in the bowl with the marinade. Use your hands or tongs to ensure each piece is well-coated. Cover the bowl and marinate in the fridge for at least 30 minutes or up to 24 hours.

When you're ready to cook, heat either a grill or a wok over high heat. If using a grill, ensure the grates are clean and lightly oiled. For a wok, add 1 tablespoon of neutral oil and heat until shimmering.

Add the marinated beef slices in a single layer. Cook for 1-2 minutes on one side without moving until a caramelized crust forms. Flip and cook for another 1-2 minutes until tender.

Remove the cooked Beef Yakiniku from the heat and plate it attractively. Sprinkle with sesame seeds, serve immediately with boiled rice and a side of chopped cucumber and tomato.