The best known example is Pickled Daikon Radish (Takuan.)
A pickling medium is made from a mixture of the bran from roasted rice, a small amount of salt, water, and a few pieces of konbu seaweed. Additional flavourings such as garlic, ginger, peppers, etc, may be added. The mixture has the consistency of damp sand. It is set aside for a week to ferment, and then it is ready to use.
To pickle items in it, you simply bury the items in it.
The pickling medium can be re-used for years.