Step by step recipe:

1. 10 min.
   Prepare 4 leeks, keeping only the white part (the green leaves can be used in another recipe).
2. 5 min.
   Cut the leeks into thin julienne strips.
3. 3 min.
   Prepare 1 shallot and chop finely.
4. 1 min.
   Pour 3 tablespoons olive oil into a frying pan on medium heat. When good and hot, add the chopped shallot, salt and pepper.
   
   Cook for 1 minute without colouring.
5. 4 min.
   Add the leeks and cook until soft, stirring regularly.
   
   Set aside.
6. 5 min.
   Rinse and and dry 1 bunch coriander . Pick off the leaves and discard the stalks.
7. 2 min.
   Put into a blender bowl or goblet: 150 ml liquid cream, 1 teaspoon lemon juice, salt, pepper and the coriander leaves.
   
   Blend until well mixed.
   
   Refrigerate until needed.
8. 5 min.
   Preheat the oven to 360°F (180°C).
   
   Prepare the fillets of sea bass: carefully remove the skin and any remaining bones. Rinse and dry the fillets.
   
   Salt and pepper on both sides.
9. 2 min.
   Lay a sheet of cooking parchment in front of you.
   
   Spread a thin layer of the julienne of leeks in the centre.
10. 3 min.
    Lay a fish filet on top and pour some of the coriander cream sauce over.
11. 2 min.
    Fold up into a parcel.
    
    Make all the papillotes like this.
12. 10 min.
    Bake for 20 minutes.
13. 
    It is always best to serve papillotes still sealed. Your guests can then open the little parcels themselves and enjoy the wonderful aromas that escape.