In a food processor, puree fish with the egg and cream. Check for seasoning. In a chilled stainless steel bowl, fold in crab and chervil into the mousse. Place in a pastry bag and stuff each mushroom. Dip each mushroom in tempura batter (recipe to follow) and in a 375 degree fryer, fry until golden brown.;
TEMPURA BATTER: In a bowl, whisk in soda into the flour until a pancake batter consistency is achieved.
EDAMAME AND TRUFFLE PUREE: Saute shallots until soft. Add chicken stock and bring to boil. Check for seasoning. Add edamames to stock. Simmer for 30 minutes until very soft. Puree in food processor with truffle oil and butter. Fold in truffles and season with salt and pepper.