On and off, I have lived in Korea for almost 2 years. I have to say the food that has challenged (and puzzled) me the most is Kam Ja Tang (감자탕), or Korean potato stew. First of all, although it is called potato stew (Kam Ja Tang), there is hardly any potato in the soup. The main ingredient is actually pig spine, and if you don't look hard enough you will miss the half dozen slices of pota..