Grinding garlic/chile/spice pastes for indian food or latin food
As for the guacamole, the ones they use for that are more properly a molcojete which is bigger & coarser than a traditional mortar & pestle and are frequently made with basalt which makes for a rougher surface. They are also used to make salsas
I used it to make garlic herb pastes for meats, esp. pork roasts.
I put some garlic cloves, olive oil, salt and whatever herbs in it and crush to a paste, them rub it on the meat to marinate before roasting or grilling.