Almost every Korean meal includes kimchi. Even breakfast. There are over 200 different kinds. Some are made with whole leaves of napa cabbage. Others use white radish cut into cubes, cucumbers, spring onions or even fruit. Each family has its own way of making it, and a grandmother's recipe is a treasured thing.
Making kimchi is a community activity. Once a year, in late autumn, families gather to make kimjang - a giant batch of kimchi that will last all winter. Parents, grandparents and children all help: washing leaves, mixing the spices, packing the jars. The tradition is so important that UNESCO has officially listed it as part of the world's cultural heritage.
Kimchi gets its tangy flavour from a process called 'fermentation'. Tiny helpful bacteria, called Lactobacillus, eat the sugars in the cabbage and turn them into a mild acid. That is what makes the vegetables sour, fizzy and easier to digest. Yoghurt, bread and pickles work the same way.
Because it is so well loved, Korea even has a museum dedicated to kimchi in Seoul. You can see jars from 100 years ago, learn how to make your own kind, and taste a flight of different kimchis the same way some people taste different cheeses.