Bake crust in a 450° oven for 5 minutes. Drain salmon liquid into a cup. Put salmon in a bowl and remove bones and skin; flake salmon. Put salmon pastry; sprinkle with lemon juice. Cook onion in the butter; transfer to the pie crust and sprinkle with parsley. Mix the salmon liquid with eggs, milk, and seasoned salt and pepper; pour over salmon. Bake quiche at 350° for 45 to 50 minutes, or until firm. Serve this salmon quiche hot.