Place a piece of napa cabbage leaf on a cutting board, slice off the tough central core. Spread 1 or 2 slices of the pork (depending on the size) over the napa cabbage. Layer with napa cabbage and pork slices alternating the orientation of the cabbage leaf each time from base to tip. Build up a stack of this combination and set aside.

With the remaining napa cabbage and pork, repeat the same process. The last set might be less layers than the other sets depending on how many napa cabbage leaves and pork slices you have, and that’s okay.

Cut each set (from the bottom side) into about 2” (5 cm) pieces and start to fill the donabe (or whatever heavy bottomed pot you might choose)from the outer side, by facing the cut side up. For the top end pieces place them top end up. Make sure to pack up tightly.

Pour the sake and dashi and spread the ginger and mushrooms evenly over the napa cabbage and pork. Spread the shio-kombu or tsukudani in the center.

Cover with lid, and set over medium heat. Cook for 35– 40 minutes, or until everything is cooked through and the napa cabbage is very soft.

Serve the dish into individual bowls at a table (with the soup), and enjoy a generous drizzle of the ponzu.

technique well explained here