For the salt crust mix:
For the filling:
For the beurre blanc:
Mix all the salt crust ingredients, except the optional egg white, together well. It’s best to prepare this dry mix two to three days in advance so it can infuse; just store it in an airtight container. It will keep for the next time, too.
Dry the sea bass well and stuff it with all the ingredients for the filling, making sure they are evenly spread out inside it.
Preheat the oven to 200°C/400°F/gas 6. You will need a sheet of silicon or parchment paper 70cm x 50cm in size; fold it so that you have a sheet of about 35cm x 50cm. Fold or crimp up the edges so they form a little lip and place the sheet on a flat baking tray.
Mix the egg white into the salt mix if using (it will help to hold the crust together, giving you a harder crust and enabling you to mould it to shape, but alternatively you could simply spray the fish with water once you have finished covering it with the mix). Put a layer of the salt mix in the middle of the paper the size and shape of the bass. Very carefully place the fish on top. Cover it completely with plenty of the salt. Bake it in the oven for about 35–45 minutes. Test it with a probe to make sure the inside is hot.
Make the beurre blanc while the fish is cooking. Place the shallots, wine and vinegar in a stainless steel pan over a high heat and reduce until only a few tablespoons of liquid are left. Lower the heat slightly and whisk in the cold butter piece by piece, whisking constantly until you have a velvety beurre blanc – remove the pan from the heat just before adding the last piece of butter. Add all the other ingredients except the lime juice and wasabi and let them infuse while the bass is baking. Keep the sauce warm, preferably by putting the pan in a bain-marie, a container of warm water – but not too warm, or the sauce may split. Adjust the seasoning just before serving and add the lime juice and wasabi. Strain the sauce through a fine sieve just before serving.
To serve the bass, crack open the crust and divide the fish between the plates; serve with the perfumed beurre blanc.