Ingredients250ml fish stockSplash of Noilly Prat200ml thick cream100g unsalted butterMethodThis is a good example of where your preparation and mise en place come into their own. Having previously made your fumet de poisson, fish stock – see Chapter 6’s recipe – you simply reduce some of it down and then thicken it with cream and/or butter.This is, in fact, a prime tenet of nouvelle cuisine as originally championed back in the 1950s by Fernand Point. He, rebelling against the Age d’Or cookery of Escoffier which had dominated the first half of the century, refused to thicken sauces with flour. “Beurre, toujours du beurre…Butter, always butter” he said, shortly before dying of a heart attack a plump, middle-aged man.So. Take a suitable quantity of your fish stock – for four people think a quarter of a litre.After cooking your fish – say, pan-frying some filets of rouget, red mullet – deglaze the pan with a little vermouth – Noilly Prat is the French cook’s weapon of choice here. Deglazing means splashing in a little liquid, barely enough to cover the bottom of the pan over a high heat and then scraping furiously at bottom of said pan with a wooden scraper to dislodge all the nice bits stuck to it. Nice bits caused by the famous Maillard Reactions, which have nothing to do with a duck.Once you’ve deglazed you add your stock and reduce it as quickly as possible to a syrupy consistency. Don’t faff around here, boil it like mad. Then, add 200 ml of thick cream, reduce the whole by half or more until it’s nice and thick. Then whisk in your butter in small cubes straight from fridge, away from the heat. Serve immediately spooned over your fish fillets.