BY SARA MOULTON
Fish en papillote is the elegant-sounding name of a staple recipe of classic French cuisine. In English, it becomes the much less elegant-sounding "fish in a bag." By any name, though, this method of baking fish is a smash.
Typically, the fish is combined with vegetables and herbs, some butter or oil, and often some wine. All of this is wrapped up in a piece of kitchen parchment and baked. The parchment keeps the flavor and moisture trapped inside during cooking, allowing the juices from the fish and the other ingredients to mingle and become a wonderful sauce.
And because the parchment is stick-resistant, the recipe requires little fat. The oil in this recipe is there for taste and texture only.
In this recipe, the few ingredients I've added to the salmon are in the service of the sauce. But if you wanted to make a whole meal in a bag, you could add sauteed mushrooms, blanched broccoli or carrots, and steamed potato cubes.
If you do add vegetables, they'll need to be precooked. The denser vegetables like carrots and broccoli simply won't have time to get tender during the 10 to 12 minutes of cooking needed by the salmon. Similarly, if wetter veggies like mushrooms and spinach aren't precooked, they'll release too much liquid in the packet and water down the sauce.
To know if the fish is done, start with the basic rule: In a 400-degree oven, give it 10 minutes of cooking time for every inch of thickness.