Marinate the chicken in the saké and soy sauce for 10 minutes. Drain and set aside. Blanch and chop the spinach. Peel and devein the shrimp, leaving the tails intact. Discard the stems of the shiitake mushrooms and quarter the caps.
To make the Dashi Custard, heat the dashi stock with the saké, soy sauce and salt until the salt is dissolved. Remove from