Prepare the Ingredients: Cut 300g of Korean fish cakes into bite-sized pieces. Thinly slice two green onions, separating the whites and greens. Thinly slice half an onion and optional green and red chilies.
Make the Sauce: In a small container, combine soy sauce, oyster sauce, minced garlic, honey, sugar, mirin, black pepper, and water. Mix well.
Cook the Dish: In a large wok or pan, heat oil over medium heat. Add the white parts of the green onions and onions, sautéing for about 1 minute. Add the fish cakes and stir-fry for about 2 minutes. Then, add the chilies and sauce, stir-frying for another 2 minutes or until most of the liquid has evaporated.
Final Touches: Turn off the heat, add the green onions and toasted sesame oil, and mix well. Taste and adjust seasoning if necessary. Transfer to a serving plate and garnish with toasted sesame seeds.