When the unexciting translation is considered—in parchment—it’s no surprise the technique isn’t more widely appreciated. En papillote, however, is a particularly effective way to cook delicate fish and mollusks. The limited cooking cavity inside the folded packet forces the commingling of aromatics, liquids and fish. But the real value is in the reveal: a plumped and golden purse pleasantly fills the dining room when pierced.
Good candidates for inclusion: any flat, white fish; chunks of meatier fish or scallops; shrimp or split langoustine; mussels, clams, cockles; any other sea creature. The ideal combination is perhaps sole or flounder topped with clams and shrimp, providing a range of seafood textures and flavors. The addition of shellfish contributes significantly to the cooking liquid, releasing its own essence, helping along the mild flat fish.
I’m not one for wild experimentation in these established preparations, although this technique is particularly forgiving of variance. The categories are carved in stone though: aromatic vegetable, herbs, fat, acid, seasoning. Fennel and tomato are brilliant in more Mediterranean preparations, but a simple mirepoix will suffice. Herbs should be fresh; parsley, chervil, thyme or oregano are the classics. Olive oil is fine; butter superior. Lemon is nice, but a splash of dry white wine is the only acid necessary. I limit my seasonings to salt and (white) pepper.
The design and construction of the parchment packet is critical. Start by unrolling and cutting a 12-inch section of parchment. Fold it in half. Clip-off the corners (fusty French technique has you cutting a semicircle or half-heart shape, but, well… the French also flute mushrooms). Layer your ingredients on one half of the sheet, retaining a two-inch perimeter of clean paper. Fold the other side over. Beginning on one side, crimp the two parchment layers together in obtuse, overlapping folds until you reach the other side. Tuck any excess under the packet.
These packets, done several hours in advance of service, can now quite comfortably wait on a sheet pan in the refrigerator. This is ample time to make a rice pilaf, go swimming, or press a few shirts before dinner. When your guests arrive, set the oven to 375 degrees; pop the pan in twenty minutes before you’d like to sit. The bags will puff and brown and, as if through alchemy, create a world-class sauce. One note: any attempt to remove the meal from the parchment to a service platter and drizzle with that sauce will fail. Instead, tear open the top of the purse and enjoy the novelty.