Bring chicken stock to a boil, stir in rice and reduce heat to simmer. Cover and cook 40-45 minutes until wild rice blooms and is tender. Drain and cool on a baking sheet then transfer to a mixing bowl.
In a skillet, heat EVOO over medium-high heat, a turn of the pan. Melt in butter then add mushrooms and saut to soften, 5-6 minutes. Add leeks, thyme and dill, and season with salt and pepper. Cook 3-4 minutes more, deglaze with vermouth or wine. Add lemon juice and transfer to the mixing bowl with rice. Stir to combine.
Preheat oven to 425F. Cover a baking sheet with parchment paper.
Gently roll out the puff pastry sheet with a sprinkle of flour. Cut 4 rectangles about 6x8 inches.
Heat a drizzle of EVOO in large, nonstick skillet over medium-high heat. Season the salmon filets with salt and pepper, and add to the hot pan. Brown the fish 2 minutes on the first side and 1 minute on the flip side. Remove from heat.
Pile some rice and mushroom topping onto each pastry rectangle in small even mounds leaving an edge all around for wrapping. Place a piece of salmon on top. Wrap and seal the bundles of salmon and set them on the baking sheet. Brush with egg wash.
Bake 15 minutes or until deeply golden. Serve with Beurre Blanc, optional, and asparagus or haricots verts alongside.