Guacamole de Molcajete

Mash the garlic in the bottom of the molcajete (lava-stone mortar) using the rejolote (lava-stone pestle). Then crush the cilantro leaves. Mix in pulp from avocado and follow with a scattering of the rock crystals. Pour in lime juice, add cucumbers, and give a few good twists of pepper. Stir together and serve from the molcajete (or any mixing bowl). Place a sampling onto round tortilla chips and top with a sprinkle of cotija (a white Mexican cow's milk cheese somewhat similar to Parmesan in texture).