Make the dill sauce:
In a bowl combine the sour cream, dill, minced onion and salt and pepper. Mix to combine and then cover and refrigerate until ready to serve.
Make the salmon pie:
Preheat oven to 350℉. Lightly grease a 12 x 15-inch cookie sheet with non-stick cooking spray.
Unfold puff pastry sheet onto prepared cookie sheet. Sprinkle with parsley, thyme, salt, and pepper.
In a sauté pan, melt 2 tablespoons butter and sauté shallots until translucent. Add spinach and sauté for 3 minutes. Remove from heat and cool mixture.
Spread spinach over pastry, top with diced salmon, and season with salt and pepper.
Roll dough as for a jelly roll, place seam side down and brush with beaten egg.
Bake, uncovered, at 350°F for 45 minutes to 1 hour, until slightly browned and flaking. Let stand 5 minutes before slicing and serving with dill sauce.