Cod baked in foil packets, also known as "en papillote," is a dish as elegant as it is simple. The fish cooks in an aromatic steam, ensuring moist, flavorful results every time. There's practically no clean up involved because the foil is discarded. You can serve the fish by placing the foil packets directly on dinner plates, allowing your guests to open the bundles and reveal the beautiful meal inside. You can use individually portioned fillets for each guest, or bake one large fillet to divide later. To save time, prepare the cod in foil packets up to 6 hours in advance and store them in the refrigerator until it's time to eat.
Preheat your oven to 400 degrees Fahrenheit.
Tear a piece of aluminum foil about 4 inches longer than your piece of fish.
Rub both sides of the fish with olive oil and sprinkle with salt and pepper. Arrange the piece of fish in the middle of the foil.
Spread flavorful aromatics on top of the fish. Thinly sliced garlic, shallots, onion, lemon and ginger all work wonderfully. Add chopped fresh herbs to the packet like thyme, rosemary or parsley.
Add vegetables to the packet to turn it into a complete meal, if you wish. Tender greens like baby spinach, bok choy and arugula will cook perfectly alongside the fish. Chopped vegetables like broccoli, carrots or zucchini are also excellent additions. You can use just about any vegetable you have on hand, as long as it's cut small enough to cook in the short time frame.
Fold the foil over the fish, sealing the edges as tightly as possible. To ensure a leak-proof packet, you can seal the fish in another layer of tightly sealed aluminum foil.
Place the packets on a rimmed baking sheet and transfer them to the oven. Bake the fish until it is opaque, about 15 minutes for 6- to 8-ounce fillets. Bake whole fillets for 20 minutes. Increase the cooking time by 2 minutes if you've added vegetables to the packet.
Remove the packets from the oven and allow them to rest for 3 minutes before opening. You can serve the fish in the packet, or scoop the fish out with a spatula and drizzle the juices on top before serving.