You can fry the bottoms, and then boil them like pot stickers; Or heat up your cup of oil in a tall pan if you don't have a fryer. The oil is too hot if its constantly popping, and making a huge mess(About 350 Degrees). Submerge, or turn dumplings in hot oil till sides are slightly tan. About 1-2 minutes. Set aside on a wire rack to cool; they'll brown as they dry(Another 8-10 minutes).

Unless you freshly made your rice cakes, let them soak for about 10 mins until soft. Meanwhile, bring your stock(or diluted fishsauce) to a boil in a pot. Add the gochujang, sugar, soy sauce, garlic, and pepper flakes. Mix, then add your rice cakes, potato and onion. Let boil for another 5 minutes, then let simmer for another 6. Add some sesame seeds and serve!