Possibly the most significant Mexican cooking tool, in my opinion, is the molcajete
: an ancient mortar and pestle chiseled from a unique basalt stone that has the ability to infuse complex flavors into salsas, pastes and guacamole. This porous-textured bowl is used to grind down chiles, seeds and herbs in order to release oils from ingredients that add a true taste difference to dishes.
I actually purchased this exact molcajete for my father after the one he inherited from my grandmother had gone completely smooth from decades' worth of use. It's authentically crafted with stone extracted from an extinct volcano in Michoacán, Mexico, by local artisans.