In a large bowl, combine the gochujang, gochugaru, soy sauce, honey (or corn syrup), sugar, sesame oil, black pepper, garlic and grated ginger until smooth.
Add the sliced chicken to the marinade and mix well until evenly coated. Cover and marinate for 30 minutes.
Heat the vegetable oil in a large non-stick frying pan or wok over medium-high heat.
Add the marinated chicken and stir-fry for 3–4 minutes.
Add the sweet potato, cabbage, onion and Korean rice cakes. If the pan becomes dry, add a splash of water. Continue cooking for 4–5 minutes until the vegetables are tender and the rice cakes are soft.
Stir in the spring onion and cook for a further 1 minute, until the chicken is fully cooked and the onion has softened.
Serve hot with steamed Korean rice or sushi rice, kimchi and fresh lettuce leaves for wrapping.