"Note: This kimchi will get more and more sour as it ages. It can be eaten immediately, but is optimal at around 3 weeks. For a more traditional kimchi, replace the miso paste with 1/4 cup fish sauce or 2 tablespoons jarred brined tiny shrimp. It's normal for the kimchi to produce lots of gas as it's fermenting. Your jar's lids may pop open when you open them and bubbles may appear in the liquid. Do not be alarmed...."