Japanese curry rice is one of my favourite food. It is both delicious and nutritious. And while it is easy to prepare (with curry roux), there are endless combinations for the ingredients, which make each curry one-of-the-kind for every household or maker.
I fantasize that recipes form identity of a secret society. Not only recipes for food, but also any procedures to construct or process things. For example, in a Mad Max-styled post-apocalyptic world the manufacturing of firearm cartridges can sustain a community.
It can also be something more subtle, like the group of students Confucius led. They hold a house of philosophy, and it serves to bond between members and interact with external forces.