It’s 23 years since Nathan Outlaw opened the Black Pig in Rock, Cornwall, when he was 25 years old. It was a long shot that everyone told him not to take – he already had a great job at the Vineyard in Stockcross, Berkshire; his wife, Rachel, was eight-and-a-half months pregnant; and he’d won a couple of prestigious young chef awards. But he wanted a place of his own; a simple menu, “bistro cooking,” he says. “That’s why I became a chef. I loved cooking, my dad’s a good canteen chef, he worked in a big paper mill in Kent, cooking for workers. I loved the physical aspect, standing up doing something. I loved the way there’s a lot of team work. I didn’t know anything about Michelin stars or being famous.” But he got his first Michelin star anyway, the year after he opened.

After that, he was a name, and it was fine dining and TV specials for many years – two eponymous restaurants in the St Enodoc hotel in Rock, the Great British Menu and Saturday Kitchen on TV, and he kept a foothold in Mayfair with Outlaw’s at the Capital in the 00s. He’s a calm cook, never big on the fireworks – “My mum always said to me: ‘you can’t be the one that throws your weight around, you’re too big’” – which is the right temperament for the food he pioneered during these tasting menu years.

When he started, people only ever cured salmon, a fish he doesn’t use these days because it’s so hard to find a decent farm (and the conditions on an indecent farm, you don’t even want to know about, but I’ll give you the keywords: overcrowding, bad feed, lice). Outlaw started curing all the catch of the area, more or less (“I’d never cure a scallop because it’s fine raw as it is”), with incredible precision – the cuts have to be immaculately even, so they cure at the same rate; he’d take them out of their brine of salt, sugar and white wine every half an hour to see how they were progressing. “Now, people are using the technique for lots of different things. Probably because I’ve showed them how to do it,” he says, and this is the only time I hear him blow his own trumpet. I suppose it’s easy to be your best self in a gorgeous, chef-tidy kitchen, on a beautiful day in Port Isaac, north Cornwall, with floor-to-ceiling windows looking right on to the sea, but even adjusting for that, the guy is an absolute honey.

With his new book, Nathan Outlaw on Fish (“The title’s quite generic, but it’s much more personal than it sounds”) – and for the restaurant and B&B he now owns in Port Isaac, he’s returning to a bistro sensibility, and it’s reminding him of everything he loves about his work. “I was always worried about getting to this stage of my career and hating it. I don’t enjoy the challenge of the industry.” (Anyone in hospitality will recognise the perfect storm, of every cost going up, but what you are able to charge the customer going down. “But in terms of the cooking, I probably enjoy it more than I ever have done. I get to teach a lot of guys, I get to work with great ingredients, and I’ve got enough good people around me that I don’t need to do anything boring.”

This is a stone-cold gorgeous book – I’ve made the sea bass en croute twice since I got back from Cornwall, which is no small thing considering it takes me half a day – and today he’s making steamed brill with pea, shallot and cider stew.

First, your fish – but never decide what you want before you get to the fishmonger, says Outlaw. Adapt your plans to what looks good, and always ask where it came from – not necessarily because you know one body of water from another, just because if they don’t know, they might not be cut out for this game. I read in a Delia Smith book years ago that you should never buy fish that smelt of fish, which confused me because I can always smell a fish if I’m looking right at it, but Outlaw nails this down: “An ozoney smell is like an oyster, or a really nice harbour, or the smell of the sea on a hot stone. You can smell that on good fish. Bad fish are a different kind of fishy, and what you’re smelling is not the fish, it’s the water it was caught in.”

Brill is a flatfish, the same shape as a turbot: “Texturally, they’re very different. With brill you can do raw and cured dishes, turbot you can’t – it’s very tough. Brill is a much more delicate fish.”

Ostentatious people call turbot the king of the sea, while all right-thinking people prefer brill. Filleting a fish like this, with its rhombus shape and frilly edges, will be daunting, and don’t even try without a really sharp, flexible knife. “The bones are not straight, so you need to be able to flex around them. With a flatfish, just follow the line all the way from the head to the tail. Through the knife, in your hand, you should be able to feel the bone; if you can’t, you’re probably cutting into the flesh. Or you’ve gone through the bone.”

You can get six prime pieces from a brill, and keep the frilly bits (and the head and bones) for stock, because that’s where the gelatine is and where the body of the dish will come from. “A lot of traditional recipes are just ‘boil the bones up’ – that’s why it doesn’t taste that great. If you roast the bones first, like you were dealing with a chicken, it’s much tastier. You get a bit of caramelisation; you get a lot of flavour. Season it, add a little bit of olive oil, put it in the oven at about 180C/350F/(160C fan)/gas 4 for maybe 25 to 30 minutes. The most important thing is only to get a bit of colour in it – if it’s singed, it’ll bring a bit of bitterness.”

When you’re dealing with shallots, get small ones you can braise whole: “nicely and slowly, give them a bit of time, they’re actually really sweet as they soften”. Outlaw isn’t “one of these butter-and-baster chefs. I don’t use a lot of dairy, apart from today – we’re going to have a huge amount of clotted cream. But I’m always trying to get a natural flavour. The lemon and butter thing, it is tasty, but it’s also a way of covering up fish that isn’t fresh.”

Chefs are going off nonstick frying pans because of those PFAs, the so-called forever chemicals, and Outlaw has a beautiful triple-layered stainless steel pan from Robert Welch, “but the difference is, you’ve got to get it hot before you put the bacon in, otherwise it will stick”. It’s all magnificently simple, once the shallots have collapsed – cider, stock, fresh peas, cream – then the fish itself steams in less time than it would take to microwave a ready meal.

“Because I’m quite finicky myself, and I was so fussy when I was younger, I bear in mind what people don’t like about fish, and try to make the seafood very accessible. Still to this day, if I was presented with a huge fruits de mer with loads of stuff on it … well, I’d eat it – but I’d find it quite daunting. And if you’re starting from zero with fish and shellfish, you’ve got to accept there’s going to be a little bit of trial and error. That’s why you should start simple and work your way up. Once you get to the fancy stuff, you’ll realise the simple stuff is better.”

Tips from the sea

If you ever see a bargain, buy it and freeze it: “Certain fish you can’t freeze – your oily fish, the fat doesn’t like being frozen, so when you defrost it, it becomes extremely fishy, and the texture just falls apart.” But brill, monkfish and other white fish can benefit from being frozen if it’s super fresh when you get it.

There’s an octopus invasion (did everyone know this apart from me?). “They’re not our native octopus, they’re from the west coast of Africa. So now, all the fishermen, when they pull up their lobster pots, all the lobster have gone and they’re full of octopus. The octopus have eaten them. The only bit of light is that octopus, cuttlefish and squid only have a two-year life cycle. When they spawn, the eggs could go with the tide and they’d move somewhere else. But they’re very sticky, the eggs, they cling to the pots. So it could be that they stay, and the dominant fish in the UK becomes bluefin tuna and octopus.” Forget what you might have eaten on a beach tourist trap, and learn to see octopus for the spectacular curiosity that it is: pork belly made of fish.

Gurnard is the best all-rounder: “It’s good for everything – barbecue, frying, curing. It’s got qualities of a white fish that people love, but then it has the oiliness that something like bass does.”

Dover sole sounds so luxurious, but you can often pick up a larger one because restaurants are all “after that perfect size for the one-piece finish”. A big one, roasted whole and rested, is a whole new experience.

Favourite utensil: the bamboo steamer
“It’s such a bargain,” Outlaw says of his hardy bamboo steamer, which goes by the name Grandma Shark, after the brand of the first one he ever bought. As light as they are, these last for ever unless you let the pan underneath boil dry and singe them. Even after that, it won’t look perfect but it’ll just have battle scars. You can get a three-tier tower, if you’re after that sort of efficiency. Outlaw makes his own cartouche of greaseproof paper, so neatly a factory could have done it, but if your style is more seven-year-old cutting paper into a snowflake, that still works.

Steamed brill with pea, shallot and cider stew

A filleted portion of brill from a good-sized fish, lightly steamed, is a comforting and pleasurable delight. Brill is such a delicate species that harsher techniques of cooking tend to dry out the edges of the fish. In this recipe, I’ve paired the fish with a subtle fennel salt that brings out its character. Beneath the fish pools a fresh but rich stew of peas, bolstered with cider and clotted cream. A wonderful, delicate plate of food, I hope you’ll agree!

Prep 20 min
Cook 50 min
Serves 4

2 tsp fennel seeds
2 tsp sea salt
8 slices smoked streaky bacon or pancetta
2kg brill, filleted and portioned into 4 x 120g portions
2 tbsp olive oil
A drizzle of extra-virgin rapeseed oil, to finish

For the pea, shallot and cider stew
50g unsalted butter
2 tbsp rapeseed oil
12 shallots, peeled and left whole
200ml dry cider
1 sprig of rosemary, finely chopped
300ml fish stock
200g fresh peas, podded
100g clotted cream (ideally Cornish, of course!)
1 tbsp chopped mint leaves
1 tbsp chopped flat-leaf parsley leaves
Sea salt and freshly ground black pepper, to taste

To make the stew, heat the butter and oil in a medium saucepan over a medium heat. When the butter is bubbling, add the shallots and gently let them colour all over, stirring occasionally, for 15–20 minutes. Don’t cook them too quickly – if they start to colour fast, reduce the heat.

Once the shallots are well coloured, add the cider and rosemary and increase the heat to allow the cider to reduce quickly. When the cider has reduced by three-quarters, pour in the fish stock and simmer until reduced by half. Add the peas and simmer for a further 20 minutes.

Meanwhile, set up a large bamboo steamer or switch on the steamer oven. Crush the fennel seeds and sea salt together in a mortar and set aside. Cook the bacon until crisp under a hot grill or in a frying pan, then set aside.

Season the brill with two teaspoons of the fennel seed salt and drizzle with the olive oil. Put the fish on a sheet of baking parchment and steam for four to five minutes.

While the fish is cooking, add the clotted cream to the stew. Bring to a simmer and whisk it in, then add the chopped herbs. Taste and add salt and pepper as you like.

To finish, ladle the stew into bowls. Peel the skin away from the brill and sprinkle the flesh with one teaspoon of the fennel seed salt. Place the fish on top of each portion of stew and add two slices of crispy bacon to each bowl. Drizzle a little extra-virgin rapeseed oil over the fish and serve, either with new or mashed potatoes.

• This recipe is an edited extract from Nathan Outlaw On Fish: A Seafood Handbook, published by Kyle Books at £30. To order a copy for £27, visit guardianbookshop.com