Prepare a wrapping
Parchment paper makes for an attractive presentation when cooking food en papillote, plus the silicone coating resists sticking. Fold a large sheet in half and cut it to form a heart shape when opened. It should be large enough to hold all the food, plus a couple extra inches.
Using aluminum foil, on the other hand, makes it much easier to create a tight seal. It's possible the acidic ingredients will react with the aluminum, but after short cooking periods, I didn’t have any problems.
Soaked bamboo and banana leaves also work well, not to mention look attractive.
Do not use wax paper or plain brown paper. They can leak and burn.
Choose lean, tender protein
Fish fillets are the classic choice for the en papillote method. They cook quickly and come out beautifully moist and flavorful. Tilapia, salmon, halibut, and trout, for example, all work well. Lightly butter or oil them and give them a sprinkling of salt. Add any spices you’d like.
Other options: lean proteins like whole stuffed fish, shellfish, chicken breasts, firm tofu, and pork chops. You might consider searing meats for color and flavor before wrapping them up.
Cuts of fish and meat should be no thicker than about an inch.
(Vegetables work too, but more on that later.)
Select flavorful accompaniments and keep it simple
It’s important that all the elements are done cooking at the same time. To make sure this happens, cut slower-cooking vegetables into thin slices or julienne them before adding the meat or fish. Another option is pre-cooking some ingredients.
Some options: scallions, fennel, ginger, red onion, shallots, mushrooms, herbs, olives, capers, orange slices, peppers, asparagus, fresh peas, garlic, lemon zest.
Be careful not to crowd the package with too many, especially those with a high water content. You could wind up with a soggy result.
Layer the ingredients on the wrapping
Lightly oil or butter the inside surface of the wrapper to prevent sticking, especially if you're using aluminum foil. If you're using parchment, layer the ingredients an inch or so from the fold on the heart shape.
A bottom layer helps insulate the protein and ensure even cooking. Try using: Swiss chard or Napa cabbage leaves, a few spoonfuls of béchamel, a wrapping of prosciutto.
Next goes the protein.
Add the quick-cooking, aromatic vegetables and herbs on top.
Create a steamy environment with additional liquids
So now that you’ve selected proteins, vegetables, aromatics, herbs, and spices that will release moisture and flavor to create a steamy vapor, you’ll need a small amount of flavorful liquid and/or added fat.
Drizzle in liquids that pair well with your other ingredients: reduced stock, coconut milk, wine, vinegar, soy sauce, citrus juice, or fish sauce.
Fats such as butter, olive oil, sesame oil, and cream will also add moisture and balance.
Fold it up tight to keep the moisture in
If you're using aluminum foil, just fold up all the edges snugly.
If you're using parchment, it takes a bit of work to form a tight seal. With the stack of ingredients on the parchment, start making very tight, closely overlapping little folds at the top of the heart and work your way around, towards the bottom. Twist and fold the bottom end over. You should leave enough space around the food to allow the air to expand and circulate.
If you get a tight seal, the package will swell up like a balloon when it cooks.
Watch it puff up in the hot oven
Place your package on a sheet pan and put it in the preheated oven.
Determining the right temperature and cooking time may take a little experimentation. Thinner fish fillets can cook in under 10 minutes at 425°F. A chicken breast will need about 20 minutes. Other factors like the amount of added vegetables and whether or not the fish is skinned will also affect the cooking time.
How can you tell when it's done? Look for a puffed-up, slightly browned parchment package. Open it carefully, take in the fragrant steam, and serve very hot.
En Papillote Successes (clockwise from upper left)
Tilapia with Swiss chard, Jerusalem artichoke, oil-cured olives, thyme, shallots, olive oil and lemon juice.
Trout with herb butter and lemon slices.
Saltimbocca-style chicken breast with sage, prosciutto, and shallot béchamel.
Firm tofu with reduced orange juice, fennel, shiitake mushrooms, chives, ponzu sauce, and sesame oil.
En Papillote Veggies
(It can work really well with vegetables too.) Whole heads of garlic turn out soft, sweet, and slightly caramelized. Cut off the tips of the cloves, add salt, pepper, olive oil, and a thyme sprig. Wrap up and cook for 45 minutes at about 325°F.
Beets come out tender and easy to peel. Toss them with oil, salt, and pepper, wrap in foil, cook for about an hour (more or less, depending on the size) at 350°F.
En Papillote Limitations
I have come to love this cooking method, but sometimes you want the color and texture that only roasting can give you. As in the case of these potatoes and chorizo.
Sliced onions, peppers, and a sprinkling of smoked paprika would’ve added flavor to the steam, but even then, I’d want them roasted. A covered casserole dish often does the trick. Like in the case of chicken breasts over (lightly pre-cooked) pasta in a tomato sauce.
To hell with it, just throw it all in one big pot. Mussels with a good amount of garlicky, wine-laced broth, for example. Having to sweat the aromatics first and being able to contain only so much liquid en papillote, makes it a bit of a hassle.
Still, I’d put mollusks with fish en papillote.