Peel, wash and slice the carrots diagonally. Clean the leek, cut into rings and wash. Cook carrots in boiling salted water for 10 minutes. Add the leek 2 minutes before the end of the cooking time and cook along. Meanwhile wash the herbs, dab dry, pluck the leaves from the stalks and chop finely.
Mix herbs and oil. Season with salt and pepper. Wash and dry oranges and limes and cut them into thin slices. Wash cod fillets and dab dry. Place 1/4 of each vegetable in the middle of a parchment paper. Place 1 cod fillet each on top and brush with herb oil. Sprinkle fillets with sea salt and cover with orange and lime slices. Wrap the parchment paper and close at the sides. Place the parcel on a greased pan of the oven lined with baking paper.
Place 1 cod fillet each on top and brush with herb oil. Sprinkle fillets with sea salt and cover with orange and lime slices. Wrap the parchment paper and close at the sides. Place the parcel on a greased pan of the oven lined with baking paper. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for approx. 15 minutes. Remove the parcel from the oven and serve immediately