Cod loin cooked en papillote with lemon, red onion and melted blue cheese.
When you open a cod parcel, a fragrant puff of steam escapes: the blue cheese has melted over the fish, while the lemon, red onion and oil mingle with the cooking juices. This recipe encloses the cod in a folded parcel that traps the steam, with bold but balanced seasoning. Allow 2 minutes of preparation and 15 minutes of cooking at 200 ยฐC, for a total of 17 minutes for 2 people. This recipe joins my collection of keto main dishes.
What is cod en papillote with blue cheese?
Cooking en papillote means enclosing ingredients in a folded parcel to trap the steam inside. This gentle, moist cooking method protects delicate flesh, concentrates flavors and creates light cooking juices at the bottom of the parcel. Here, cod, a lean white fish, cooks in a sealed parcel, either in the oven or on the barbecue over indirect heat, with lemon, red onion, fresh herbs and a drizzle of olive oil.
To assemble, three thin lemon slices and a little red onion form the aromatic base. Patting the cod thoroughly dry helps it hold its shape, and the crumbled blue cheese melts directly onto the flesh. When the parcel is opened, the flesh should be opaque, tender and flake easily, the cheese melted or softened, and the juices fluid, with no browned crust.
The origins and foundations of the dish
Cooking en papillote protects the main ingredient by trapping steam around it. Once the parcel is sealed and heated, steam circulates inside, keeping the aromas enclosed and infusing the fish and its accompaniments. Cod is well suited to this method, as its lean, delicate flesh needs careful cooking and benefits from being surrounded by citrus, herbs and olive oil.
This version uses the classic technique and gives it a bolder character with blue cheese, whose salty, robust flavor enhances the seasoning without overwhelming the fish. In a preheated oven, use 15 minutes at 200 ยฐC as a guide. On the barbecue, cook with the lid closed over indirect heat to protect both the underside and the center of the fish.
The main ingredients
Cod loin is the main ingredient, with two generous pieces for two people. Its mild flavor pairs well with lemon, herbs and blue cheese, but its lean flesh dries out if the steam escapes; patting it dry before cooking gives you less watery flesh and less diluted juices.
The 75 g of blue cheese add character, a salty note and creaminess as they melt over the fish: crumble the cheese finely and divide it between the two portions to avoid an overly strong bite. Bleu d’Auvergne and Fourme d’Ambert both work well, with intensity varying according to maturity.
Half a small red onion, cut into very thin half-moons, softens during the short cooking time and adds a sweet note. Wash the lemon and zest it if desired, then cut it into six thin slices, three per portion, to flavor the base without overpowering it. Fresh thyme and oregano round things out, two pinches of salt are enough because the cheese already adds salt, and two drizzles of extra virgin olive oil mingle with the juices.
Technique tips and serving
Sealing the parcel is the key step: use PFAS-free parchment paper in the oven and aluminum foil on the barbecue, with sheets large enough to seal tightly without crushing the filling. A poorly sealed parcel lets steam escape and dries out the fish; on the barbecue, a sheet of parchment paper against the filling limits contact between the lemon and the aluminum. Slice the onion and lemon very thinly so they release their flavor quickly. In the oven, cook for 15 minutes at 200 ยฐC after preheating, bearing in mind that the thickness of the loins and their starting temperature affect how quickly the center cooks.
When opening the parcel, keep your face and hands back, as the steam escapes quickly; the fish is cooked when it is opaque in the center and flakes easily. Serve it in the opened parcel or in a shallow bowl, with the onions and melted cheese, spooning the juices over it. Zucchini, green beans, cauliflower or a green salad with a lightly salted Thai dressing all work well, with no need for an extra cheese sauce. It is best eaten straight away; store leftovers with their juices in an airtight container, removing any aluminum foil in contact with the lemon, and reheat once, covered. Allow 388 calories and 6 g of net carbs per portion.
For everyday keto cooking, here are all my low-carb recipes.
Cod en Papillote with Blue Cheese
Ingredients
- 2 cod loins
- 75 g blue cheese
- 0.5 small red onion
- 1 lemon
- 4 sprigs fresh thyme
- 2 large sprigs fresh oregano
- 2 generous pinches salt (Celtic sea salt)
- 2 small drizzles extra virgin olive oil
Instructions
- Preheat the oven to 200 degrees Celsius. Alternatively, use a barbecue that is already up to temperature.
- Wash the lemon and grate its zest. Then cut it into 6 thin slices.1 lemon
- Cut the onion into very thin half-rings.0.5 small red onion
- Prepare two sheets of baking paper or aluminium foil.
- Place 3 lemon slices on each sheet, then top with the onion.
- Pat the cod dry and place it on top of the onion.2 cod loins
- Crumble the cheese over the fish.75 g blue cheese
- Scatter the herbs and salt over the cheese and add a tiny drizzle of olive oil.4 sprigs fresh thyme, 2 large sprigs fresh oregano, 2 generous pinches salt (Celtic sea salt), 2 small drizzles extra virgin olive oil
- Seal the parcels tightly and place them in the oven for 15 minutes. If using a barbecue, cook over indirect heat with the lid closed for best results.
