Seasoning a granite mortar and pestle, with intuition for the steps and their order There are many procedures for seasoning a new unpolished granite mortar and pestle from Thailand.

Some sites recommend:


Wash without soap and dry completely
Crush garlic, maybe with salt and peppercorns. Let it sit for 30 minutes to 24 hours, then
rinse, and dry.
Add either wet or dry rice into the mortar and mash the rice to a paste/powder. Repeat until rice paste/powder remains white.


Another site recommends:


Rinse with clean water (no soap) and let it air dry.
Grind a small handful of white rice. Discard and repeat until the
rice grinds white.
Add 4 cloves of garlic, mash and muddle them together.
Then add 1 teaspoon of cumin, 1 teaspoon of salt and 1 teaspoon of
pepper to the garlic. Grind it all together and discard.
Rinse once more (without soap) and allow to air dry.


Cooks Illustrated just recommend dry white rice.

What is the best way to do it? What is the logic for each step and the sequencing?
The rice, salt, peppercorns and garlic aren't hard enough to polish the granite.  There are hardness scales such as the Rockwell hardness scale and Mohs scale for minerals. 

What you are really doing is grinding the granite pestle against the granite mortar. The purpose of having some material in the process is just to get the granite particles to mix into material being ground. The notion is avoid packing the ground off particles onto the surfaces of the mortar and pestle.