Every spring the Joseon kings headed to Seonnongdan, an altar where they prayed for a good harvest. After the ritual, a special beef and vegetable soup (seolleongtang) was served to the assembled peasants. Seolleongtang is still popular today.
When Japan abolished the Korean monarchy in 1910, the palace tteok (rice cake) makers were sacked, so they opened small shops around the Nakwon Arcade, just north of Tapgol Park, and sold their tteok to the public. The shops are still run by their descendants.
Budae jjigae or Johnsontang is a unique dish that originated in the hungry years after the Korean War when tins of ham, sausages and baked beans were bought on the black market around American army bases (such as Yongsan) and mixed with noodles and vegetable scraps to make a meal. Try it at Nolboo in Hongik.
The royal court was based in Seoul for over 500 years and royal cuisine dishes include gujeolpan and sinseollo. Generally the cooking style is less spicy than usual and requires elaborate presentation.