If using frozen rice cakes, thaw them in water for about 30 minutes. Drain and set aside.
Heat vegetable oil in a large pan or skillet over medium heat.
Add the garlic and sauté until fragrant, about 1 minute.
Add the fish cakes (if using), cabbage, and green onions. Stir-fry for about 2 minutes.
Stir in the sesame oil, soy sauce, gochujang, gochugaru, and sugar.
Pour in the water or chicken broth, and bring to a simmer.
Add the rice cakes to the pan. Cook, stirring occasionally, for about 10-15 minutes, or until the sauce thickens and the rice cakes are heated through and slightly chewy.
Sprinkle sesame seeds over the top.
Garnish with additional chopped green onions and sliced boiled eggs if desired.
Enjoy your meal!