Viggo Mortensen is in his socks – he likes to go shoeless whenever he can – and is making a cup of tea. If this does not seem a thing of note, you’ve never watched Viggo brew. He carefully portions out green leaves from his own pouch into his personal silver vessel – a modern version of the South American mate gourd – then decants the water into a silver Thermos, adding the leaves to brew. “I’m ready to go,” he says, pulling his vessel close.

I mean, obviously he’d have been ready to go five minutes ago if he’d just dunked a tea bag in a cup with a slosh of milk like most of us do, but it’s clear Viggo likes to do things on his own terms and to his own very precise standards. You just have to look at his CV to see that. Viggo became an internationally fancied and bankable star as Aragorn, king of men, in the Lord of the Rings trilogy starting back in 2001. It’s a reputation he’s cemented over the years, in large part with another trio of films – A History of Violence, Eastern Promises and A Dangerous Method – all directed by David Cronenberg. Though he received an Oscar nomination for Eastern Promises in 2007, Viggo never capitalised on the earning potential the LOTR franchise offered. In fact, that idea is baffling to him. He says he only took the role of Aragorn to please his son, Henry, who was around 10 years old at the time.

Given the choice, what Viggo wants above all else is to tell a story he thinks is interesting. “I don’t really look for movies based on the budget or the nationality or the language,” he has said. “I just want to be in movies that I wouldn’t mind seeing 10 years from now.” Looking at the films he has been in since he made his name, it’s fair to say his vision of enduring storytelling is not one seen in the romcoms and blockbusters that typically make for box-office hits.

Jauja, the film we have met to discuss, is possibly one of his least commercial yet. It’s an Argentinian-Danish movie directed by Lisandro Alonso, an award-winning young director, and co-written by Alonso with Fabian Casas, an Argentinian poet. “Jauja” is a Spanish word with Arabic origins which roughly translates to Neverland. After he’s patiently clarified the pronunciation (“How as in how you doing? And huh as in uh-huh,”) Viggo explains that the promise of Jauja was used as propaganda by the Spaniards who conquered South America in the 16th century.

‘What else would I do?’: as Aragorn in Lord of the Rings: Two Towers. Photograph: AP

“It was hard to convince people to go there. You’d either die on the way or die when you got there. You never got to go home. So they tried to make it sound like the ideal place. Something you’d dream about seeing or achieving. But you never really get what you’re looking for, do you?”

The film is about a Danish captain stationed in a remote Patagonian army outpost. He’s travelling with his 15-year-old daughter and when she vanishes into the pampas, he goes on a desperate quest to find her. Viggo stumbles and sweats through the unforgiving landscape and a series of surreal encounters. At one point he follows a dog through the mountains – chasing not his own tail, but someone else’s.

Viggo’s lack of physical vanity has become a recurring theme in his work. On film he’s been beaten up (Eastern Promises), starved (The Road) and kicked in the balls (A History of Violence), but he can’t imagine work being any other way. “What else would I do?” snorts the 56-year-old. “Those films where I’m the hero with a 20-year-old girlfriend? I go for what needs to be there. Often people are desperate or ridiculous rather than heroic, so I do what needs to be done.”

Jauja is a beautiful film – lit like a Technicolor classic and surprisingly funny – but also baffling. I went to the loo during the screening and, when I returned, for a moment I thought I’d walked into the wrong auditorium because the film had changed so completely. “It’s nonlinear,” agrees Viggo. “But even people who resisted it and didn’t think they liked it find there’s a resonance on an intellectual level. You can get existential about it. What’s it about? Well, you keep thinking about it. Most movies don’t do that.”

Viggo’s animation and enthusiasm as he talks about the film are contagious. He’s very smart and articulate and his intensity is interestingly at odds with his laidback appearance – his scruffy jeans and faded San Lorenzo football shirt (Viggo is a huge football fan and the Buenos Aires team was his first love), and the ratty friendship bracelets that slither up and down his arm as he drinks his tea.

In The Road with Kodi Smit-McPhee. Photograph: Allstar

Jauja is also a personal project for Viggo. Though he was born in New York, he grew up in Argentina with his American mother Grace, Danish father Viggo Sr, and younger brothers Walter and Charles. His father worked as an agricultural manager and, though they mainly lived in Buenos Aires, they also spent time in Chaco in the rural north. “We’d go on camping holidays over the Christmas holidays in the area where Jauja was shot, just our sleeping bags in the car,” he says. “It made me really happy to be on a horse in that landscape again.”

Viggo left South America aged 11, when his parents divorced and he moved to upstate New York with his mother and siblings. The move was a shock: to lose that Spanish culture, the TV, the football. He and his brothers mainly spoke Spanish, but then they were living near Quebec. He adapted – learned some French, started supporting the Montreal Canadiens hockey team – but it seems unsurprising that he now mainly lives in Madrid with his girlfriend, actor Ariadna Gil (best known here for the film Pan’s Labyrinth).

Making a movie is not always about being paid – there is no limit to what you can learn

Working on Jauja made him think about his father a lot. “In the film I speak Spanish with a thick Danish accent, copying my father. I was raised there so there were connections for me in terms of culture, language and landscape. I knew those things would be assets for me and for Lisandro.” Did it make him think about his parents’ split? “Maybe subconsciously. I certainly thought a lot about our life there.”

Even without the personal connection, Viggo approaches each film as a learning experience. “Making a movie for me is not always about being paid, but it is a new university course. There’s no limit to what you can learn. I mean, it’s perfectly fine for an actor to say I’m just going to learn the lines and get on the horse, but I happen to enjoy digging deeper. In this case, I already knew about 19th- century Danish history and the wars the captain would have fought, so I went to Denmark and met with antiquarians and military historians. I found the uniform he would have worn and also picked out a medal. It was only given to soldiers who served in 1848-64 against the Prussians.”

With his son Henry. Mortensen says he only took the role of Aragorn to please Henry who was 10 at the time. Photograph: Matt Baron/Rex

For Viggo, this research is pretty superficial. He slept outside in his costume for the first few days of the LOTR shoot. For the big-screen adaptation of Cormac McCarthy’s The Road he went one further and slept outside in sub-zero temperatures wrapped in nothing but a tarpaulin and always made sure his shoes were soaking wet before filming, for added discomfort. While researching Good (2008), in which he plays a German professor working with the Nazis, he drove more than 1,000 miles around Germany and Poland visiting concentration camps. To get under Freud’s skin for A Dangerous Method, he not only learned to write like the psychoanalyst but also bought first editions of the books that the good doctor would have had on his study shelves.

“I just think,” explains Viggo, “that the more realistic and specific you are with the details, the more universal the story becomes.”

Much of Viggo’s LOTR money was sunk into Perceval Press, an independent publishing company (named after the knight who stars in his favourite part of the myth of the Holy Grail). Perceval produces albums, art books and poetry collections by obscure artists, and the company recently diversified into film with Jauja, the second film it has been involved in.

Viggo’s own art books, poetry and albums are also available on Perceval. He was a published poet before he set up the imprint and his art had already been shown around LA (you can see his paintings in the 1998 film A Perfect Murder. He played an artist and, of course, created the work for the film). Perceval’s biggest profits come from Viggo’s own artistic output – though whether that’s because his fans really love his spoken-word albums or because they fancy him and would buy anything he released is hard to tell. His latest album, Under The Weather, came out last month, dedicated to feminist author Ti-Grace Atkinson and Albert Camus.

Perceval Press’s website is interesting even if you’re not in the mood for buying a book of paintings of endangered species by an Iranian artist. It’s a repository for Viggo’s political and world views, too. He regularly posts features, news stories and poems which he thinks will interest visitors. Currently the home page is a jumble of pieces about Israel, Benjamin Netanyahu’s re-election and climate change.

‘The more realistic and specific you are with the details, the more universal the story becomes’: in his latest film, Jauja. Photograph: Rex

“Putting that stuff up there makes me pay attention,” he says. “I concentrate when I’m reading the newspaper in case there’s something I can take from it. It’s like having a camera. I’ve carried a camera since I was a teenager and whether you’re using it or not, it means you look at composition, think about what around you would work well in the frame. The pieces on Perceval are just things I think are interesting to read. I’ll put up pieces I don’t agree with – conservative, right wing – if I think they’re well written. I’m not saying what I think, I’m asking questions and giving you the opportunity to ask yourself how you relate to this.”

This is a nice idea, but not strictly true. Viggo has always been fairly outspoken: no one would be in any doubt about his left-wing political affiliations. “Yeah, I’ve been called antisemitic and I got so much shit for speaking out against the Iraq invasion, but it was a huge waste of material resources and manpower.”

One of my favourite stories about Viggo comes from 2005. He heard that Californian mother Cindy Sheehan had driven her motorhome to Texas and parked outside George Bush’s family home in the hope of talking to the president about her son, who had been killed in Iraq. Viggo decided to show his support, so he flew out of LA and turned up unannounced at her motorhome with fresh vegetables, mineral water and a copy of George Orwell’s Animal Farm (to read, in case she had to wait around before meeting Bush). He only spoke to Sheehan for 20 minutes because he had to go back to LA to pick Henry up from school. Sheehan said she was a bit surprised when Aragorn turned up on her doorstep, but she appreciated the gesture. Viggo dedicated his next album, Intelligence Failure, to her.

You have to admire Viggo’s intentions, no matter what you think of the end results. Whether he’s stumbling through a desert looking for life’s answers, bringing his own tea set to an interview or flying across the country for a 20-minute chat, the man knows what he wants. As we finish, I tell him I think he has a pretty nice life – he basically gets to do all the things he enjoys. He shrugs: “Yeah, but if people weren’t interested in that stuff, I’d be doing it anyway. You just have to go ahead and do it, don’t you?”

Jauja is in cinemas now

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