When is a fish done?

Before starting in my current role as a chef de partie at a chic restaurant in south London, I read the reviews. Most emphasised the elegant food and village-like setting. One, by a prominent critic, was overwhelmingly positive except to say this: the fish was a little overcooked.

This criticism stayed with me. Having long worked in professional kitchens, it was only after withdrawing from a career in academia that I had given cooking my serious attention. If this was to be my focus, I realised, then I should know for certain when a fish is overdone. But without any formal training to fall back on I fizzed with self doubt.

Recipes often call for cooking a fish until it is “done”, which I know from my time in academia to be approaching tautology. Unlike pork and chicken, where chefs tend to follow the official health advice (cook to above 70C), or beef (about 55C for medium rare, 60C for medium) consensus on the cooking of fish is comparatively slippy. Government advice suggests it should be cooked to 63C, but it’s an open secret that no serious restaurant takes any notice.

When the time came to cook fish at work, I asked my head chef how he quantified the elusive state of “done”. He handed me a thermometer and told me a fillet is perfectly done when it’s served at 50C. Simple. But catering textbooks will tell you that fish can be eaten from raw (the safest method is to freeze it first) through to boiled, baked and fried. So who’s to say what’s right?

It’s a question that Priya Deshingkar raises when I visit her in Brighton, having travelled to my nearest stretch of coastline in my quest for culinary knowledge. Deshingkar, a professor of migration and development at Sussex university and a successful supper-club host, tells me of her irritation at an episode of MasterChef in which a judge told a contestant of Indian descent that his fish was overdone. This is a common complaint. Compared with terrestrial proteins, the muscles in fish are meant to work at colder temperatures, causing them to fall apart and dry out under far less heat than it takes to cook chicken or beef. But it also reflects a distinct cultural preference.

“I appreciate the fact that the judges are experts, but they’re experts in what they know,” Deshingkar says. “There’s a tendency to apply a universal yardstick to everything they’re judging.” 

She prepares for me a whole bream in which the slashed skin is rubbed with layers of spices and lemon juice and then cooked over a medium heat in a cast-iron pan for at least 15 minutes. I recreated the dish at home and, in the name of science, jabbed a thermometer into the beady-eyed fish. Its flesh gave a reading of 79C. Yet the contrast between the soft meat and crisp skin was satisfying and the taste bright.

“The MasterChef judge would say this is overcooked,” Deshingkar tells me as she plates up. “But who decides that? And on what basis?” Perhaps the closest thing that western chefs have to an accepted standard for cookery is the one provided by a French tyre company. In the UK, out of the 169 restaurants with one or more Michelin stars, only five are filed by the Michelin guide as specialising in fish and seafood. Nathan Outlaw is one of the chefs in this small crowd.

“We don’t use thermometers for the fish,” Outlaw tells me over Zoom. “It’s all eye and touch.” Clearly, it’s an “if you know, you know” kind of thing. “You’re looking for a translucent centre,” he says, “so it looks moist, it looks sort of juicy. That’s when you know it’s perfect.” Reassuringly for the thermometer-inclined like me, he adds that a fillet served close to 50C is “bang on”. 

I confess to Outlaw that once, in the middle of a busy service, a fish I had cooked according to these criteria was sent back to the kitchen by a customer who described it as raw. “It happens,” he says. “But I always try to explain to a customer that you can pretty much eat any seafood raw. You know, it’s not going to hurt you. And in fact it’s probably better.”

His restaurants in Cornwall serve tasting menus with fish and seafood often prepared without the use of heat at all. But he can’t recall the last time a dish was rejected. Perhaps his two Michelin stars (one per restaurant) have lent him the authority to tell customers that what he serves is correct. “I think fish is beautiful when they’re sort of half cooked, half raw,” he tells me. The French have a term for that: mi-cuit.

But why is the French way the authority when it comes to the done-ness of fish served at restaurants in Britain? Why do chefs and food critics expect fish to be 50C, à la Michelin, rather than much hotter, as per the fish served in India?

If the UK has a native standard for fish cookery today it is the kind which is fried in batter and served with chips (a fusion food that combines fried fish from Spanish and Portuguese Jewish refugees, and Belgian fried potatoes). But that, according to my research, results in a very hot fish. Piercing a freshly cooked cod from my local chippie with a thermometer revealed an internal temperature of just over 68C. 

Perhaps, like much else in Britain, these standards have to do with class. Diane Purkiss, a professor of English literature at Oxford university and author of English Food: A People’s History, certainly thinks so. “The idea of rare meat spreads sideways into fish as an index of luxury,” she tells me over email. “It’s a way of being certain that what you are paying for is fresh.” These standards are probably also generational: “For a certain generation of people the great thing was to prevent food poisoning by cooking the item until it begged for mercy. But for a later generation, maybe unwarrantedly secure, it’s not seen as necessary.”

So fish served at 50C is not only a matter of personal preference. Much as it did in the past, cooking in this way distinguishes the restaurant, the chef, the consumer and the critic from popular and older tastes as well as styles of cookery defined as “ethnic”. In India, how food should be cooked is not only a matter of the region you find yourself in, Deshingkar explains, “It’s also a matter of caste and class.” Taste is intersectional, she suggests, and authority on that is therefore relative. The same can be said of Britain — and of fish.

It took only a few shifts at the restaurant for me to discover that understanding the desired temperature of a fish was only the start of the poissonnier’s labours. In the kitchen, a chef cooking fish is required to watch anxiously as orders buzz in then estimate how long a table will take to eat its starters — two starters for three people: better get a move on; a large table of older customers: no need to hurry — and check how long the other chef cooking mains will take to do their part.

The fish cook must compute other variables: the thickness of the fillet, the heat in the pan, the preparation of the garnishes, the temperature of the kitchen, the resting time in which the fish continues to cook by three or four degrees. Ensuring that not only one portion of fish, but several across multiple tables appear in the dining room at approximately 50C is a satisfying everyday miracle. Such is the work required to uphold our standards of taste.

Lewis Bassett is the host of “The Full English” podcast

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