Cut the daikon into circles about 1.5 inches thick. Score the tops crosswise to about halfway down being careful to not go any further.

Choose a heavy pot, either stainless steel, a Le Creuset type or ceramic. You want it to be a snug fit for all the daikon to sit in a single layer. You'll need a heavy lid that fits well. Add as much daikon as necessary to fill the bottom of the pot. You will need to increase the amount of sauce accordingly depending on how big your pot is and how much daikon you are cooking.

Spread the kombu on the bottom of the pot and add about half an inch of water.

Arrange the daikon cut side up. Place pot on medium heat. Cover. Bring the pot to a boil and then immediately reduce heat to allow the liquid to simmer. Let the daikon slow cook until they are fork tender. They are ready for the sauce when a paring knife slides in easily. This may take 20 minutes, or longer, depending on the size and freshness of the daikon. In true nishime cooking, the lid isn't lifted during the cooking process so the energy can stay in the pot and go into the vegetables. This creates a super strengthening dish. In reality, I might lift the lid once or twice just to make sure the daikon isn't running out of liquid and that it is still simmering. Find your own way with this. You don't want it to burn! You can use a flame deflector if that helps you prevent burning.

While the daikon is cooking, mix remaining ingredients in a small bowl. Add a little water if needed to create a thick, spreadable sauce.

When the daikon is tender, remove the cover and spread each circle evenly with the sauce. Try to keep the sauce on top of the daikon so it doesn't slide off and mix with any liquid that is left. Replace cover and cook for another 3-5 minutes.

Remove from heat and serve.