Food vendors along a side street
The first thing you notice about korean street food is just how much there is. It is not like seeing a lone hotdog stand by a big intersection. The vendors line up for blocks, each selling only one or two kinds of food. Typically, the food is served on a plate, utensils are provided, and you are expected to finish the food at the stand.
Probably the most common thing is a tteockbokki, which includes rice noodles, hard boiled eggs, and flat fish noodles (odaeng), all drenched in a spicy red sauce. Like all street food here, it is a a cheap option (about 2 bucks) which will definitely fill you up. Tteockbokki stands also usually serve odaeng on a stick. Busan, being the biggest port city, is famous among Koreans for its odaeng. Interestingly, bowl-cups are provided for people to drink the water used to boil the odaeng noodles. The warm odaeng water has a strong fish flavor, but seems to help if your mouth is burning from the spice.
This is bundigi, or silkworm larvae. This little bug is boiled in big, steaming, pungent pots and served in a paper cup. You can stab the little critters with a toothpick, unless you prefer to dump a lot in your mouth all at once. At least they're dead. HOWEVER, I know for a fact that live silkworm larve is sometimes served with Korean bbq (where eaters grill their meat at the table). Here, the silkworms are still alive and moving, before you plop them on the grill.