Trying to pin down Werner Herzog's career is an impossible task. Since his turbulent early years making the likes of Fitzcarraldo (1982) – shot in the Peruvian jungle with muse Klaus Kinski – he's mastered myriad cinematic forms, from a documentary in the Antarctic (Encounters at the Edge of the World, 2007) to thriller Bad Lieutenant: Port of Call New Orleans, in which Nicolas Cage starred as a maniacal, crack-smoking cop. Today most people know the 70-year-old, Munich-born auteur as the critically acclaimed documentary maker of films like Grizzly Man (2005), Cave of Forgotten Dreams (2010) and Into the Abyss (2011).

Fewer know him for his acting, but since 1998 he's been popping up in the unlikeliest English-language movies, from 2008 poker mockumentary The Grand to a short film the following years as the voice of a plastic bag. But it's his role as The Zec, the unflappable criminal overlord up against Tom Cruise in mystery thriller Jack Reacher that's going to have you squirming in your seat. Herzog used his deadpan turn of phrase to tell us why he's so good at being bad.

You're very scary as Russian capo The Zec.

That was the point. The only point.

Did you have any inspiration for the character?

No, it's all standardisations of course. Russians are very sweet people, very deep, very different than you would imagine. I know what I'm talking about because I’m married to a Russian woman from Siberia.

Tell us about The Zec's signature scene – he tells an underling to chew off his own fingers...

That scene was longer. I was very quiet and just kept encouraging (the victim) and the studio got scared. They wanted PG-13, which means no sex, no physical violence, no swearing, no blasphemy. And I'm very quietly inviting him to eat his fingers off – it was so scary the studio wanted to cut it down. (Writer/director) Chris McQuarrie cut it down and still the studio was scared about it. So we used a third, even more cut-down version and they're still scared.

If you find it scary then everything is good.

How did you get into the character of The Zec?

I could literally step from this table and if there were a camera and actors ready, I would step into it and I would be scary.

As such an esteemed filmmaker yourself, is it tempting to tell everybody what to do?

No, I wouldn't interfere at all. Absolutely not. And I have no problems following direction. There was one tiny, tiny moment where I made a remark that was picked up, but I shouldn't even have said it.

Did Tom Cruise apologise for pointing a gun in your face?

No, that was part of the deal. We are in movies.

Did you know he's a big fan of yours?

I didn't know that. He's very respectful and apparently has seen some of my films. But he's seen some acting of mine and he apparently wanted to have me as a real badass, a really bad and dangerous character. They have much larger parts for bad guys but they have weapons, and they needed somebody who looked dangerous before he even spoke.

What's changed in the business, for better or worse?

Changes are coming. I see it and I don't want to grow old about certain things. Two nights ago I did live streaming of a rock concert (by The Killers) over the internet. Eighteen cameras, no post-production. So I set the visual styling, and we had internet connectivity so the audience could participate and send in photos, which was part of the show. I'm always curious about what's coming at me. Of course there have been huge changes in the last 45–50 years of cinema: great innovations like digital effects, although I do not use them. There's phenomenal possibility out there. Audiences have changed, drastically.

But a good story is still a good story.

Of course, and that's going to outlive anything. Whatever is coming at us in forms of digital effects and franchised moviemaking, the long-range survival is great storytelling. That's what's good about Jack Reacher.

Is acting just for fun or does it give you a different perspective on directing?

The answer is very simple: I love everything that has to do with cinema. I like writing a screenplay, directing, editing and producing, I just love it all. I do what comes at me swinging most wildly and then I deal with it. I've never had a career because I've never planned step one, step two. It's all come at me like burglars in the night. And you're there in your kitchen and you hear the noise and if one of them comes at you swinging more wildly you have to deal with that one first.

Is that how you've come across most of your projects?

Take Grizzly Man. I swear to God I was not looking for a film. I'd been in the office of a producer who had been very friendly to me and I paid him a courtesy visit and after ten minutes I got up to leave and reached in my pocket, and there were lots of papers and half-eaten lunch salad and I realised my car keys were not in my pocket, they were somewhere on the desk. We were looking for my car keys and he spots something and pushes it to me and says, 'Read this, we're planning a very interesting film.' So I read it and ten minutes later I went straight back and asked about the status of the film, who was directing it. The producer, who is also a director, said, 'I'm kind of directing it,' and I knew then and there he wasn't completely sure. So I stretched my hand to him and said, 'I will direct it,' and I was in business. I was not looking for a film – I was looking for my car keys.

Are you a journalist at heart?

No, I am a poet. If you look at Into the Abyss, I wanted to interview a man on death row, and the authorities had no objection because I came without a catalogue of questions. I wanted a discourse with this person who was going to be executed eight days later and had no idea what I was going to say to him.

Were there any similarities between working with Klaus Kinski and Tom Cruise?

Kinski was an extraordinary professional and so is Tom Cruise. Of course there was some other problems with Kinski but bottom-line, he was a phenomenal professional, and it's always very easy to work with great professionals. Tom Cruise has an enormous intensity.

Would you like to direct a film with Tom Cruise?

I would need a real good story, one that would fit. I wouldn't randomly have him in a film where he wouldn't be the right one.

Your work has primarily been in documentaries lately. Do you have a passion for telling the truth?

No, it's just that in the last ten years I've made more documentaries. I've also made five feature films in the last ten years and that's easily overlooked because some of my recent documentaries were very successful, and all of a sudden people think you make documentaries. I just make movies.

You're working almost constantly. Are you a workaholic?

That word couldn't be more wrong, because I work very calmly and quietly. For example, on Bad Lieutenant my days of shooting were normally over by 2pm or 3pm, not a single hour over time. I brought the film in two days under schedule and $2.6 million under budget, which is unheard of in Hollywood. Now the producer wants to marry me.

My team got nervous, asking, 'What about the coverage?' I had to ask my assistant what the term meant. Is it something to do with insurance? No, no, no, they said, shoot from this angle here and that angle there. I said no, I've shot everything I need for the screen. At one point Nicholas Cage said, 'Silence everyone for a moment.' Everybody falls silent and he says, 'Finally, somebody who knows what he’s doing.’

So what do you think of someone like David Fincher who does 60, 70 takes?

Who is this?

Zodiac, Fight Club, Se7en, The Social Network…

I haven't seen any of his films. I do not know who he is. But let him do it if the result is good.