(for 2)

2 Fillets of Brill (or Turbot or Bass) at least 225g (8oz.) each.
Two tablespoons of white wine vinegar for the poaching water.

For the Beurre Blanc;

1 Good Handful of Fresh Chervil
3 Scallions
2 Tablespoons White Wine Vinegar
1 Lime
½ Glass White Wine
175g (5 oz.) Hard cold salted Butter.

If you want to serve vegetables with this get them ready in advance and keep them warm.

¾ fill a frying pan with water, add the vinegar and bring it to the boil. Once it has boiled turn it to a low simmer.
Carefully grate the zest from the lime and squeeze the juice.
Finely chop the scallions and the chervil.
Cut the butter into dice.

When you are about 8 minutes from eating then, and only then start cooking,

Slip the fish into the simmering poaching water.
Put the vinegar, lime juice and white wine and the scallion into a pot (not aluminium-or it would make the sauce grey)
Boil these together hard until reduced by about half- this will take 2 to 3 minutes.
Now start to whisk in the butter a little at a time and allow each addition to emulsify before adding the next.
You can leave it on the heat but don’t let it boil too fast as it can separate.
Once you have beaten in all the butter then beat in the chopped chervil and the lime zest and take it off the heat.
At this stage the fish should be just perfectly poached so take these out, drain carefully and put onto plates before you spoon over the sauce.

A bit of a fiddle maybe but well worth the effort.