To cook the fish

Out of a double thickness greaseproof paper, cut 4 large fish about the size of a dinner plate, keeping a join in the middle so that the paper opens out to make 2 fish joined. Lightly butter paper, place Mahi-mahi fillets on one side, top with vegetables and asparagus. Pour a little lemon juice over each and one tablespoon of champagne. Finish with lemon zest leaves. Season with salt and pepper. Brush egg white around edges of paper and seal together to encase fish. Place on a baking tray and cook in a hot oven for approximately 8-10 minutes depending on thickness of fish.

To make Champagne Sauce

Place egg yolks, vinegar and water in a stainless steel bowl and whisk over a double boiler using a balloon whisk, until thick. Remove from heat. Gradually mix in warm melted butter beating well after each addition. Allow to cool completely. Lastly fold in softly whipped cream and bubbling champagne and enjoy!