Place the water, soy and sake in a large saucepot over a medium flame. Add the kombu and simmer until the kombu softens. Add the carrots and daikon, simmer until the carrots and diakon just soften (about 2-1/2 minutes), then remove from the flame. Discard the kombu, and reserve the carrots and daikon. Add the mushrooms and shaved bonito (or dashi flakes) and soak until the liquid comes to room temperature. Remove mushrooms from dashi liquid, thinly slice the mushrooms and set aside.
Place 1 cup of mushroom dashi in the bottom of a small wok. Set a bamboo rice steamer over the dashi. Bring the dashi to a simmer over a medium flame. Place the bass fillets in the steamer and cover. Steam 6 to 8 minutes or until the bass is just cooked. Meanwhile, place the remaining dashi in a medium saucepot over a medium flame. Add the carrots, daikon, mushrooms, mustard greens, and kombu battera. Bring to a simmer. Divide the broth and vegetables equally into 2 warmed bowls. Arrange the carrots and daikon lattice style to support the bass. Lay the bass over the lattice and sprinkle with fleur de sel.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.
Recipe courtesy of Michel Nischan, Heartbeat Restaurant at W Hotel