Many vegetarians might not know this, but kimchi is usually not vegetarian because shrimp, oysters or fish sauce are frequently added to give it extra flavor. These are amazing flavors of savory umami-ness, and they are the same flavors I try to replicate and bring back in my version of vegan kimchi. I do this with a mixture of miso paste and seaweed, which will add savory flavors of seafood and the sea back into the kimchi.
I would say the only weird part of this recipe is that you leave the kimchi out on your kitchen counter for two days without refrigeration. But the salt you sprinkle on helps preserve the cabbage and the longer you ferment, the more sour the kimchi.
Some last words are that I researched both fresh and vegan methods of making kimchi along with the more traditional ones. I personally like to err on the side of tradition since it has the benefit of time and experience, so a lot of the techniques you see are what Koreans use still today to make the fermented cabbage.