Traditional “wellington” is a beef tenderloin surrounded by mushroom duxelles (cooked pureed mushroom filling) and pate, all encased in puff pastry. This version is easier - the time it takes to cook the salmon matches the time it takes for the puff to bake.
TIP: The wellingtons are best hot from the oven right after baking. Leftovers can be reheated for 15 minutes in a 325°f (160°c) oven.