Thanks iannon, Saladin, and Cory.
The bowl there is carved from a solid block (round exterior really) of clay. The solid chawan "blank" is carefully formed into the correct proportions and surface shape, then I impress the flower stamp into the exterior surface. Then let it air dry so that the exterior wall is kinda' stiff but the inside is still soft. Then I use a variety of tools to remove the interior clay and shape the interior. (Long slow process!) Last step is carving the kodai with a straight "knife" of split bamboo.
Apply Oribe glaze outside and a real Nuka glaze made from rice husk ash inside, and wood fire in the correct chamber in the noborigama (not too much reduction or fly ash).
There are other chawan I have in the show too. All with boxes, wrapping cloths, and "pedigree sheets".