For a fun lunch, buy 10 brass coins (₩5000) at the cafe about halfway along this old-school covered market. You'll be given a plastic tray with which you can then go shopping in the market. Exchange your coins for dishes such as savoury pancakes, gimbap (seaweed covered rice rolls) and tteokbokki (spicy rice-cake stew).
You can buy more coins, if needed, and use them (or cash) to pay for rice and soup (₩1000 each, kimchi is free) back at the cafe.