Soak the rice cakes (tteok) in water for about 30 minutes until they soften. Drain and set aside.

In a mixing bowl, combine gochujang, soy sauce, rice wine or mirin, sesame oil, sugar, garlic powder, ginger powder, and black pepper. Whisk until smooth.

Heat a large skillet or wok over medium-high heat and add vegetable oil. Once glistening, add chicken thighs and stir-fry for 5-7 minutes until browned and cooked through.

Toss in sliced onion, carrot, and cabbage into the skillet with the chicken. Stir-fry for 3-4 minutes until tender yet crisp.

Gently fold in the soaked rice cakes and prepared sauce, stirring to coat. Cook for an additional 3-5 minutes, allowing flavors to meld.

Remove from heat, garnish with sesame seeds and green onions. Serve directly from the skillet.