Molcajete can be purchased at a Mexican supermarket for ~$20, or online or at a cooking store ~$50.
Add a few pieces of diced jalapeño, a few leaves of cilantro, and some onion to the molcajete.
Grind the onion, cilantro and jalapeño into a paste. This will season the molcajete.
Add 2 chopped avocados to the molcajete.
Mash until avocado starts to turn into a paste, leaving some chunks.
Add more diced onion, jalapeño, and cilantro leaves to the molcajete. Use the stone or a fork to mix into the avocado paste.
Add sea salt and pepper to the avocado mixture.
Add 2 remaining chopped avocados to the mixture. Squeeze 1/2 lime on top of avocado mixture. Gently mash with molcajete stone or a fork, leaving chunks of avocado.
(Optional) cover with plastic wrap and refrigerate for about one hour before serving.
Serve slightly chunky guacamole with salty tortilla chips, on toast, meats or anything else you can dream up.