Damien Hirst has arrived early for lunch at Scott’s in Mayfair, the only man in a room of suits wearing a T-shirt and jeans. We are to be joined by Mark Hix, the chef and restaurateur. In February, they opened a restaurant in Hirst’s Newport Street Gallery in Vauxhall, south London. It was here at Scott’s that the partnership came about. “I was sat here having lunch outside and Mark pulled up on a scooter,” Hirst explains. “He said, ‘How’s your restaurant going?’ I said, ‘Shit: I just had to get rid of the chef.’ He said, ‘I’ll do it.’”

The new restaurant, Pharmacy 2, references Hirst’s previous pill-themed venture with PR man Matthew Freud in Notting Hill, which opened at the height of the artist’s shark-and-Saatchi fame in 1998 and closed in disarray five years later. Hirst has had plenty of previous with chefs: a partnership with Marco Pierre White in the ownership of the Soho institution Quo Vadis also ended predictably badly, but before Hix arrives he insists this time things will be different. He’s stopped drinking for a start (“best thing I ever did”). And the new partnership is more like a marriage. Wisely, he just lets Hix – for 17 years chef-director of Caprice Holdings (which includes Scott’s) – do what he wants. “Mark tells me what to eat,” he says. “He gives me cod chitterlings all the time.”

Hix arrives on cue, and they resume what seems an ongoing double act, Hirst cracking wise, Hix his lugubrious straight man. Watching them talk is a bit like watching two men dip in and out of an improvised stage show. From time to time, Hirst will tell a filthy joke, or hold two plates to the sides of his head in his “mouse impression”. Hix has seen it all before.

Hirst Did you have a big one last night? I tried to meet my son in Pharmacy 2 and it was shut.

Hix I saw your booking.

Hirst I keep forgetting we are not open Sunday nights. I was there having a coffee, went up to the museum, and when I came back all the chairs were up on the tables and my son was sat on his own… Is this still your menu?

Hix Not any more. All that’s left of me here is the art I commissioned.

Hirst [turning to a big surreal painting, by Steven Claydon, behind him]: What’s this here? Why has the bird got lightning in its beak?

Hix Because it has bitten through that telephone cable …

Hirst Brilliant. That’s all I needed.

Hix What are we eating, boss?

Hirst I’m having native oysters to start.

Hix I might have smoked eel, then.

Hirst I want the fish and chips but I don’t like skin on my fish.

Hix Get them to take it off.

Hirst No. That’ll go in the article. “Hirst insisted on having the skin removed from his fish.” It’s a southern thing, leaving the skin on. But I don’t want to make a scene. I’m not American.

Hix I might have ray wing.

Hirst [to the waitress]: Six natives and the fish and chips please.

Hix Can you ask them to take the skin off his fish? He has a phobia, it’s a northern thing.

We talk about a few of the parallels between artists and chefs, creating from scratch, running a team, restlessness, deadlines. Hirst’s Sensation group of young British artists did their arrested growing up during the 1990s renaissance of British cooking in London’s East End. When did the pair of them meet?

Hirst says he can’t remember. “Certainly since I’ve had restaurants I’ve always complained about them to Mark, he’s like my agony aunt. He calls my restaurant in Ilfracombe “Dillfracombe”, because I’m always moaning that the chefs insist on putting a bit of dill or whatever on top of the fish. Mark has offered to sort it out for me, my dill issue.”

Hix We met in the bad days, the absinthe days.

Hirst I never got on with absinthe. It didn’t seem to work.

Hix I do absinthe jelly for art parties. I have these brain jelly moulds. You’ve seen them, Damien …

Hirst Have I fuck. I have a Victorian ice cream skull mould. You could have a go with that.

Hix Have you not seen the absinthe jelly?

Hirst No, and I’ve been to your parties.

Hix I did one at the Royal Academy schools. The artists loved it, even the ones who don’t drink.

Hirst I don’t drink. But I’d have an absinthe jelly. Some people who don’t drink won’t have wine in their sauce. It’s more bottles of tequila and multiple grams of cocaine that I avoid.

Hix You can’t get drunk on a sauce.

Hirst Unless, I guess, you asked for it in a pint glass on the side …

As he is speaking, and sizing up the art on the walls, Hirst is flexing his shoulder and rubbing his arm and wincing. I ask him what’s wrong. He says he has a poorly bicep. Trapped nerve he thinks. He does a lot of yoga.

Hix I do pilates.

Hirst Liar.

Hix I do. Every week. An hour. Woman in the East End.

Hirst I do yoga. Iyengar. Three times a week. An hour and a half each. I used to slouch a lot, now I slouch a bit less. But it’s trapped a nerve. I’ve got to get a fucking scan.

I explain how the previous week I had a scan on my own shoulder, a bit of bone had chipped off and it was removed with keyhole surgery. Hirst is thrilled. “I love an MRI!” he says. “I’m making a scanner in white marble. It’s called Portal. Full size. It’s from a series called Modern Miracles. I love the way you slide in and you hear all the grinding and thumping. You lie there desperate for a wank to relieve the tension but you can’t move.”

Hix It’s amazing how many actual pharmacists we get at the Pharmacy. We get retired ones, just qualified ones …

Hirst I’m just texting to get some painkillers sent in from my driver. I’ll crumble them on the oysters. Here’s an idea: you could do Viagra oysters at the restaurant.

Hix Are we still going to do Pharmacy 2 in Notting Hill?

Hirst We could try to go back to the old place! It’s funny. When we opened the Pharmacy I thought the restaurant would be around forever but the art wouldn’t last.

Hix It would work in Notting Hill now.

Hirst Not with Matthew Freud it wouldn’t. I said to Matthew at the time: I’m not doing this for the money. And he went: neither am I.

Hix That is why it turned into a shit restaurant. But it would work now.

Hirst I got angry at a bouncer in the old Pharmacy because they caught me doing drugs in the toilet and he refused to throw me out because it was my restaurant. I said, “You’ve got to: drugs are a big problem in this place.” He wouldn’t do it. I said, if you don’t, I’m going to sack you in the morning. It was like one of those classic dilemmas. He wouldn’t do it. He was right, too, I didn’t sack him. I woke up with my tail between my legs, as ever.

While he slurps his oysters, Hirst is watching the door for his driver with the painkillers. I tell him I’ve got some Voltarol in my bag. “I’ve already had one of those,” he says. “When you get to 50 you can’t get through the day without at least a couple of Voltarol.”

Hix Pharmacy would be good in Berlin.

Hirst It would be good everywhere. But you’ve got to get the chips with truffles right. I was there with my bird the other day and she gave me the truffles off her chips. I said, ‘Don’t let Mark catch you doing that.’

Hix We got a great bad review from the Daily Beast.

Hirst I liked the headline: “Damien Hirst’s food is worse than his art”. I took that as a compliment, because the food is great.

Hirst says he has long been plagued by headlines. He’s currently working on a project to retrieve some artworks he buried at sea off the coast of Mexico 20 years ago. “Things I’d made I wanted all covered in coral,” he says. “Fake things, real things. Treasures.” Is he diving down to get them?

“No,” he says quickly. “I’ve always been terrified that the headline will get me: ‘Damien Hirst eaten by shark.’ I’m not a snorkeller. I get worried in the pool. I have to have one foot on the bottom.”

His fish and chips arrives. The skin has been removed under the batter. He is delighted.

Hix I had to do one of those 20 questions on the phone for an interview this morning.

Hirst “What’s your biggest regret?” I always liked Leigh Bowery’s answer to that: “Unsafe sex with 2,000 men.”

Hix You can’t think on the spot.

Hirst I don’t have many regrets. My last drinking relapse was 10 years ago – 9 November. I was in the Groucho Club and I knew it was near the end for me so I went through the lot behind the bar. Then I had the nightmare from hell, seven days of horrors. And then when I came out the other side I knew I would never drink again. But the worst thing was that I forgot to have a Ricard, my favourite drink of all time. I regret that to this day. Why didn’t I have a Ricard? It haunts me.

Hix They make this thing called Cornish pastis now.

Hirst Do they? Get some in to the restaurant. I’ll do you a knock-off Ricard label.

As the meal goes on we talk some more about the relationship between art and food. “I’m jealous of chefs,” Hirst says. “Because food is like art without the evidence. Twenty years on people will say, ‘I remember this amazing meal I had …’”

Does he cook?

“I do a good Thai curry. I grow lemongrass in Devon. I’ve got two polytunnels. It is a miracle, the polytunnel.”

Hix I really like those hexagonal greenhouses.

Hirst They look great. But they don’t work like a polytunnel. If I had to change my name I would change it to Polly Tunnel.

He goes into a Yorkshire accent suddenly: “I’ll not have a son of mine wearing bloody earrings. You’ll be wearing your mother’s knickers next.”

Food has always been important to him he says, but it has often got him into trouble. “I used to rob the allotments and make shepherd’s pie at home. I once got sacked for nicking a rack of T-bone steaks from this place where I worked. Another time I was in the mortuary doing anatomy drawing. One day I brought a human ear out; it was all black, the medical students had been at it. Hugh, who I still work with, brought a pizza and when his back was turned I put this ear in the middle of it. He cut a circle out around it and ate the rest of the pizza.”

The talk moves on to some work Hirst is making for his “endless series”. His latest spot painting involves a million dots a millimetre in diameter in different colours. It took him three months to count them, he says. I wonder how often people try to pass off fake pictures?

“I’ve got a company called HIAC, the Hirst Authentication Committee,” he says. “People fake my signature and put a painting on eBay. I‘ve got a beauty that just came in. [He hands round his phone which shows a wild portrait of a lunatic with staring eyes] ‘Dear Sirs, Can you confirm or deny…’”

Is he ever not sure?

“No. But people fake everything. It’s weird how times have changed. I remember a mate buying a painting off me for 50 quid because he had a job and I didn’t – that was so sweet. I remember buying a roll of bubble wrap with Angus Fairhurst, my friend who killed himself, and us thinking, ‘We’ve made it!’ because we could afford to wrap up our own work. We had half the roll each.”

Does he ever go back home to Leeds?

“Not really. My mum moved down to London, so there’s no point. I don’t need it for my work. It’s not like Margate and Tracey [Emin]. That gets difficult: I mean she’s a dame or a fucking lady or something now, isn’t she?”

You’re not going to be Sir Damien?

“No. It’s not for me. I got offered a CBE and turned it down. My mum went mad with me. Then I got the phone call that said: if it was the knighthood would you accept it? I said: you’ll never find out. Would you accept it, Mark?”

Hix I suppose you do.

Hirst I couldn’t. Come the revolution you’ll be hanging from a lamppost. Anyway, I’ve got a house in Regent’s Park, and my kids already call me sir. What more do you need? The house is next to the mosque. I showed a picture to my mum, she said, “It’s a terraced house!” We grew up in a terrace in Leeds before we moved to a semi. She said, “All that money and you’ve bought a terrace.”

Hix We could do a Pharmacy in it.

Hirst How about in Paris?

Hix Venice? LA we should do. You could get an old pharmaceutical factory, make it a hotel.

Hirst Do you smoke weed, Mark? I can’t do it. One spliff and I have to sit behind the cooker and wait until it wears off. I remember Charles Fontaine cooking me lobster when I was on magic mushrooms. It was like some massive alien cockroach on the plate.

Hix says he doesn’t smoke weed; and also that, regrettably, he has to leave. He tries to get to at least three of his London restaurants each day and he is at Pharmacy 2 tonight. Time was, he says, lunch would have carried on until 3am tomorrow rather than 3pm this afternoon. Hirst looks slightly wistful at the idea. He flexes his shoulder. He still hasn’t got his painkillers. But he has plenty to look forward to. “I’ve got the dentist at four o’clock,” he says brightly. “Bridge work needs doing. My dentist wears a kilt.” It seems he can hardly wait.

Pharmacy 2 Restaurant, Newport Street, London SE11 6AJ; 020 3141 9333