1. In a large saucepan over medium heat, combine wine, water, celery, celery leaves, peppercorns, and bay leaves. Add the salmon and bring to a light simmer; cook until just done (still pink inside), about 2 minutes. Pull the flesh from the bones and skin, watching for small bones. Put the salmon in a large bowl. Discard skin and bones. (Save stock for fish soup.)

2. Saute the leeks over medium heat in 2 tablespoons of the butter until soft. Saute the mushrooms over medium heat in 3 tablespoons of butter until dark brown, 8 to 10 minutes. Add both to the salmon meat. Soak the cellophane noodles in hot water for a few minutes, then drain well and chop. Melt the remaining butter and add to the salmon mixture, along with the noodles, dill, salt and pepper to taste, and lemon juice. Mix well and cover. Refrigerate until ready to bake.

3. Heat oven to 400 degrees. Divide puff pastry in half, and roll out on a lightly floured board to 1/8 inch. Cut 6 4-inch-by-4-inch squares and 6 5-inch-by-5-inch squares. Gather the scraps and roll them out again; cut into decorative shapes.

4. Line a baking sheet with a piece of parchment paper. Place the smaller pastry squares on the sheet. Mound filling on each, leaving a 3/4-inch border. With a pastry brush, dampen borders with ice water. Top each square with one of the larger pastry squares. Crimp the edges to seal tightly. Brush the decorations with ice water and place them on the coulibiacs.

5. Beat together egg yolk and cream, and brush over coulibiacs. Bake for 30 minutes, or until puffed and golden brown. Serve with lemon juice and melted butter.