Smoked Salmon and Chive Mascarpone Mousse with Pink Pickled Onions

Preparation

1. To prepare the salmon:

   Step 1

   In a small saucepan sprinkle gelatin over lemon juice and soften 10 minutes. In a bowl with an electric mixer beat together mascarpone and 1/2 cup sour cream until combined well. Quarter eggs and with back of a spoon force through a coarse sieve into mascarpone mixture. Add horseradish and stir well.

   Step 2

   Add remaining 1/4 cup sour cream to gelatin mixture and heat over moderately low heat, stirring, just until gelatin is dissolved. Add gelatin mixture to mascarpone mixture and stir well.

   Step 3

   Cut about one third salmon into strips and arrange 1 in every other ridge of a 3-cup brioche or other mold, letting ends hang over edge. Chop remaining salmon into 1/2-inch pieces and fold with chives into mascarpone mixture. Spoon mousse into mold and fold ends of salmon strips over top. Chill mousse, covered, at least 2 hours, or until firm, and up to 2 days. Run a thin knife along inside of each ridge of mold and dip mold into a bowl of hot water a few seconds. Invert a plate over mold and invert mousse onto it.

   Step 4

   With a slotted spoon arrange pickled onions decoratively on and around mousse touching each other, and keeping covered with plastic wrap.

   Step 5

   Brush mushroom rolls all over with melted butter and rearrange, seam sides down and barely touching, in pan. Chill mushroom rolls, covered, at least 1 hour and up to 1 day.

   Step 6

   Preheat oven to 425°F.

   Step 7

   Bake mushroom rolls in upper third of oven 15 minutes, or until golden. Halve rolls crosswise and tie a chive around each half.

2. To make the pink pickled onions:

   Step 8

   In a saucepan barely cover onions with cold water. Bring water to a boil and simmer 1 minute. Drain onions in a colander and return to pan with vinegar, salt, and cold water to just cover. Bring liquid to a boil and simmer 3 minutes. Remove pan from heat and cool onions in liquid. Pickled onions may be made 1 week ahead and chilled in liquid, covered. Makes about 2 cups.