I just picked up a heavy-heavy molcajete (mortar & pestle) at COSTCO for 299 pesos. Neatly packaged. Sad but true...made in China, imported to the USA then again to Mexico.
From the Oaxaca ladies...
Only one way to break in a new molcajete...
One cup of raw rice into the bowl
Start mashing and dragging the pestle
The rice grains need to be crushed to flour
And your arms are going to feel like they're falling off.
If it takes sessions over two or three days to make rice flour
Then so be it.
Dump and then wash out the flour with water.
Every Mexican lady I asked about this was adamant about the "seasoning" of the bowl.
No rice? Use rock salt.
Blender? Ni modo. Blenders do not crush
Guacamole has never tasted better, use tostadas instead of totopos (corn chips) tostadas have no salt or artificial garbage and they taste like corn not cardboard.