If you have seen K-drama(Korean drama) at least once before,you would have seen people eat this red, spicy looking food at the market stalls, snack bar or food trucks. This food is called tteokbokki(떡볶이) and is one of the most common/classic/traditional street food in Korea.
Tteobokki, for those of you who might have not heard of it, is basically a little spicy, stir-fried ricecake with some sauce. Quite a lot of foreigners think it looks like pasta or gnocchi. But the main ingredient is actually ricecake, which is called 'tteok/ddeok' in Korean. It normally comes with fishcake, boiled eggs, spring onions, carrots and gochujang sauce.
It is one of the most common street food or snack in Korea so that's simply why you cannot see any Korean dramas without eating tteokbokki scenes.
It has multiple varieties when it comes to flavour. Firstly, you can have it with a lot of soup(soupy gungmul-tteokbokki), just a little bit (basic and classic version), or even completely without(gireum tteokbokki=stir-fried in oil).
Also, for some of who doesn't like spicy food like foreigners, you can make it with soy sauce or curry paste, etc.
Thirdly, You can put some extra ingredients in there, which makes the dish even better. You can put ramen noodle, chewy noodle(jjolmyeon, 쫄면) or cheese as one of toppings.
Normally, it sells as a condition of pre-cooked, but these days, there are some restaurants where you can make on your own tteokbokki, which is called 'on the spot tteokbokki(즉석 떡볶이)'. You have various choices in which toppings you would put so if you have already tried normal tteokbokki, it's a great experience to have one!
As it is very comon, you can find it very easily wherever you go in Korea. So if you find it whilst you are wandering around in Korea, please do give it a go. First taste might not be that familiar, but you can get used to it and soon you will love it.