In a saucepan melt butter over medium heat. Cook onion and mushrooms, stirring occasionally, for 5 minutes or until softened. Add stock, water, salt and pepper. Bring to a boil. Add wild rice, return to boil. Reduce heat, cover and simmer for 35 minutes. Stir in long-grain rice, simmer, covered, for 25 minutes or just until liquid is absorbed and rice is tender. Let cool.
Trim spinach, rinse, shaking off excess water. In saucepan with just the water clinging to leaves, cook spinach over medium heat for 8 minutes or until wilted. Drain in sieve, pressing out moisture. Chop, toss with lemon juice and nutmeg. Cut salmon crosswise into 4 pieces. Separate some skin from flesh. Holding skin, insert knife at 45 degree angle. Slide along to cut fillet from skin.
Lay 1 sheet of phyllo pastry on work surface, keeping remaining phyllo pastry on work surface covered with damp cloth. Brush with about 2 teaspoons of the butter. Place second sheet on top. Brush with butter.
About 1-inch from 1 long side of pastry, spoon 1/2 cup rice mixture lengthwise into 3-inch wide strip, leaving a 4-inch border at each short side. Arrange 1/4 of the spinach over rice. Top with 1 piece of salmon.
Fold 1-inch border over filling, fold each side over and roll up. Place, seam side down, on greased baking sheet. Brush with butter. Repeat with remaining ingredients to form 4 packages. Bake in preheated 425 degree oven for 15 to 20 minutes or until golden.
Meanwhile, in saucepan, boil vinegar, wine, shallots, salt and pepper for 5 minutes or until reduced to 2 tablespoons. Reduce heat to low. Vigorously whisk in butter, a few cubes at a time, until thickened and smooth. Stir in parsley. Serve with salmon packages.