Kimchi is a fermented pickle, like sauerkraut and the fermentation process is key to its flavour. It’s elemental in Korean food and in Momofuku food and you can make it with almost anything. In northern Virginia, where I grew up, my mom and my grandmother made it with blue crabs (which was totally gross, in case you’re wondering). But some kind of seafood is often added to kimchi to help kick-start the fermentation process. Raw oysters are common, as are squid, shrimp or yellow croaker. We use the jarred salted shrimp that look like krill and have a strong but still appealing and sweet shrimp aroma. A little goes a long way and a 500-gram jar will last even an avid kimchi maker a while, so take the time and hunt one down.