Nabemono is a Japanese hot pot. This version is similar to the nabemono they produce in Hokkaido, and it features miso, salmon, shiitakes, leeks, winter radish and spinach. If you don't have dashi, a Japanese fish stock, you can make your own, or substitute any fish stock or even chicken stock.
2medium leekswhite and light-green parts only, sliced thin
For the Dashi
Place kombu in a pot, if using, and cover with 1 ½ quarts filtered water. Allow the kombu to soak for 15 minutes to soften it.
Turn on the burner to a moderately high flame. When the water begins to bubble, stir in bonito flakes, and remove from heat. Cover and allow the bonito flakes to steep in the water until they to the bottom, about 10 minutes. Strain the broth, composting the bonito flakes.
For the Nabemono
Preheat oven to 275 F.
Rub miso paste along the interior of your nabe pot, clay baker or Dutch oven. Arrange salmon, leeks, shiitakes, radish and spinach in the pot. Pour hot dashi over the salmon and vegetables. Cover and transfer to the oven. Allow the stew to cook 15 minutes or until the fish is done to your liking.
Remove the pot oven, lift lid and toss in spinach. Return lid to the clay baker and allow the spinach to wilt in the residual heat of the soup - about 5 minutes.
Ladle into individual soup bowls and top with salmon roe.