Set up a steamer. Place oysters and eggs in a food processor. Mix and add cream while moving. Season. Pour mix into a large mixing bowl. Fold in mushrooms, chives, peas, and truffle oil. Cook a little bit in the microwave to check seasoning. Fill tea cups half way with the mixture add 1 whole oyster and then top off with the mixture. Place in the steamer for 25 to 30 minutes or until custards are set.
Coat a hot saucepan with oil and cook onions and garlic until soft, about 3 minutes. Season. Add chicken stock and bring to a boil. The stock should taste salty, like pasta blanching water. Add the peas and cook until soft, about 15 minutes. Do not over cook. During the last minute, add the spinach. Immediately transfer to a blender and blend at high speed. Add the butter, blend and check for seasoning. Mix in the juice and reserve hot.
PLATING: Place bowl on doiled plate. Ladle sauce on top of hot custard to completely cover.
Recipe adapted from Ming Tsai, The Blue Ginger Restaurant