Little life hack I discovered. Sauerkraut makes excellent kimchi substitute in ramen/guk/chiggae.

Since I have no kimchi, I've been adding 2-3 cups of sauerkraut to my ramen, and oh my, it does a very good job replacing kimchi. It has the same texture, and the same fermented taste we all love. Gotta add something spicy though, but Shin ramen takes care of that.