A molcajete is a Mexican mortar and pestle. There is an extensive Wikipedia article about molcajete.
It's typically made from volcanic stone and is used for grinding things and is great for guacamole.
It requires seasoning, much like cast iron skillets.
There were a bunch of different sites with a whole range of methods for seasoning, but I mashed a few together and ended up with this process:
- Grind down dried corn
- Grind down dried beans
- Grind down 2 batches of dried white rice
- Grind down soaked white rice
- Grind a mix of cumin seeds, garlic, green onion, chili pepper and rock salt and allow paste to sit for 12 hours or so
After each batch of stuff, rince and dry.