Chef John's Salmon in Parchment
Cooking fish in parchment paper is incredibly simple, and yet fairly terrifying for a novice cook. Since the seafood is encased in paper, there's really no good way to check if it's done. The good news: if you use a large, center-cut salmon filet, about 8 or 9 ounces, and cook it for 15 minutes at 400 degrees F, you're going to be very, very close.
I served mine with a very light mustard aioli, which was simply mayonnaise, Dijon mustard, lemon juice, and a touch of garlic.