I fell down the perilla seed hole and got some green and red shiso from eBay to try. I also found a (local-ish to me) Asian variant seed distributor Kitazawa Seed https://www.kitazawaseed.com/seeds_perilla.html which stocks Japanese and Korean perilla seeds for those growing and cooking their way around the world. I've seen Nukazuke kits but this is the first time I've seen a tsukemono seed kit https://www.kitazawaseed.com/chef_gardens.html