If you can’t find mizuna, dandelion greens, mustard greens, or even spicy arugula, make nice, if different, substitutes. Sato-imo is a small, hairy taro potato. Uncooked, it has a slimy texture that some find mildly irritating to the skin. Cooked, it has a velvety texture. Small wax potatoes, Japanese sweet potatoes, and turnips can all be substituted.
- 2–3 small Japanese sato-imo, peeled and quartered
- 2 carrots, peeled and cut into inch-long pieces
- 1 4" daikon, peeled and sliced into 1/2" thick rounds, then quartered
- 5 dried shiitake mushrooms
- 1-1/2 C dashi
- 1/4 C sake
- 2 T mirin
- 2 t rice vinegar
- 1/4 C soy sauce
- 5 leaves napa cabbage, washed and sliced on a bias into 1 1/2" thick pieces
- 10 pieces mochi, about 50 g each (Mochi comes fresh or dried in wrapped packages. Pieces range in size, but are typically around 50 g.)
- 1 bunch mizuna, washed, trimmed, and dried thoroughly, and chopped into 2" pieces
- + shaved dried bonito (katsuoboshi), to taste
The night before, fill a large stockpot with water and bring to a boil. Simmer the sato-imo, carrots, and daikon until fork-tender but still firm, about 20 minutes. The same night, or up to one hour before cooking, soak the shiitakes in 1 cup of water. Refrigerate until needed. The longer you soak them, the stronger the flavor will be.
Remove the shiitakes from the bowl, reserving the liquid. Remove the stems and quarter them.
In a large stockpot, combine the shiitake liquid with two cups of water, dashi, mirin, rice vinegar, and soy sauce. Bring to a simmer.
Add the rehydrated shiitakes and vegetables and simmer, covered, for about 5 minutes. Add the napa cabbage and continue to simmer for about 5 more minutes, or until the cabbage is tender but still bright in color.
Meanwhile, heat a cast-iron pan over medium-high heat. Add as many mochi to the pan as will fit without crowding. Using chopsticks, push the mochi around to prevent burning, and patiently wait for them to toast and puff up, flipping them periodically. If mochi start to burn, lower the heat. The mochi are ready when they have puffed up and their sticky centers are soft enough to poke with a chopstick, about 5 minutes.
Place 1 or 2 pieces of mochi into each person’s bowl and top with a ladleful or two of soup, making sure to include 1–2 pieces of each kind of vegetable to the bowl. Garnish with fresh mizuna and katsuoboshi, and serve immediately with a cup of sake.