It's a physical tic she uses to emphasis a point or add drama to an anecdote, but it has the effect of making her already sizeable personality just that little bit bigger. The air fairly fizzes with energy as a result.
Much of the theatre she makes could be said to employ the same gesture and to the same effect. Casting its own arms wide it embraces not just drama but live music, dance and all manner of bravura visuals. They call it "cross-form" in the lingo. To audiences, meanwhile, it offers a beckoning welcome, an invitation to gather round, cast off any expectations about traditional theatre and become immersed in a story - told, of course, the Bissett way.
For Roadkill, her 2010 piece about sex trafficking, that meant a "stage" that was actually a dingy flat off Edinburgh's Leith Walk. Up close and intimate is one way of describing it. For 2012's Glasgow Girls, based on the true story of a group of Drumchapel teens who fought a friend's deportation to Kosovo, it meant approaching subjects like detention centres and dawn raids by immigration officials through life-affirming song-and-dance routines.
"I just don't see the boundaries between art forms," says Bissett simply. "I don't want to use the word 'stuck', but some people just work within the realms of a well-written play and the text is gospel. I respect that form and it's a certain way to present theatre. But for me, the text isn't gospel. I really love working on the visual level, the musical level, the physical level as well as with text. All of those have equal weight for me."
So the verb "making" is appropriate where her theatre is concerned? "Yes. It's about building it in layers and layers. The writer is a part of that, but they're one element within those layers."
We're talking in Easterhouse, in a side room of the Bridge arts and leisure complex where the 39-year-old is rehearsing her new work, GRIT: The Martyn Bennett Story. It opens at the Tramway in Glasgow this week and it's based on the life of the revered Scots-Canadian folk musician, who died of Hodgkin's Lymphoma in 2005 aged just 33.
If the title seems workaday, you've probably guessed that its realisation will be anything but. Bissett has already told me about a scene involving a trapeze artist, there are several other circus performers involved as well as dancers and when I ask about stylistic influences she mentions Fuerzabruta, the Argentine spectacular - part rave, part circus - which wowed audiences at the 2007 Fringe.
GRIT itself is a collaboration with choreographer Dana Gingras, of avant-garde Canadian dance company Animals Of Distinction, and it has a script by Kieran Hurley based on interviews with Bennett's mother and widow, his friends and former bandmates, and even the doctors who cared for him. The lead role is taken by Sandy Grierson, fresh from his triumphant performance playing another Scottish iconoclast in The Beautiful Cosmos Of Ivor Cutler. The music is all Bennett's, however, with the show's title coming from the name of his final album.
Grierson knew Bennett, though not well. Bissett attended the Royal Scottish Academy of Music and Drama (RSAMD) in Glasgow a few years after him but their paths never crossed. So what made her want to tell his story?
The idea came from a conversation she had during the production of Glasgow Girls with Rick Standley, who played bass guitar in the house band. He told her he hadn't performed such a mixture of musical styles since his other group, maverick classical ensemble Mr McFall's Chamber, had recorded an album of arrangements of Bennett's music.
"I went home thinking: why has nobody done a story about Martyn Bennett?" she says. "What he was doing in his music was celebrating the ancient heritage of Scotland, but he was also very internationalist in his outlook and I thought that seems timely right now because Scotland is looking at itself. We're looking at our past, we're trying to work out who we are, we're constantly talking about this notion of identity and we're looking at the ways we're connecting with the outside world."
Bissett admits that among the wider Scottish public Bennett's music isn't that well known. Some of the younger actors she auditioned didn't know it at all. But what will catch at people's minds and emotions is the very human drama of the story. Once again, this is a theatrical work that will present itself with its arms spread wide, all-encompassing in its themes of life, love, death, music, passion, family and tragedy.
"Although Martyn died of Hodgkin's lymphoma, he was diagnosed with testicular cancer in his early 20s so for most of his adult life he was battling mortality. And yet the rate and the passion and the bravery with which he was creating this music - that for me is the drama and the part people will connect with," she says. "There's a quote by him: 'It's not how long you live, it's what you do with the time you've got'. I think we can all connect with that on a very basic level." Besides, she adds, sometimes "things just have a moment when they're ready to be told".
Cora Bissett's own story begins in Glenrothes. Her father was a medical sales rep, her mother a primary school teacher and she has two sisters. Her background and her childhood were (her phrase) "bog standard". Things
changed when she left school, however. She was all set to take up a place at Glasgow University when, aged 17, a career in rock music beckoned instead.
The band was called Darlingheart and when Bissett joined as a singer, they were still rehearsing in a garage in Kirkcaldy. But a demo tape they had recorded and sent to a manager in Edinburgh found its way to a major label, Phonogram Records. They liked what they heard and before you could say "Big in Japan", they'd been signed.
"I'd applied for a place to study English but I wasn't very passionate about it. I knew it wasn't right. But I got in this band, got picked up by Phonogram, and whisked off," is how Bissett tells it.
Soon she was on tour supporting a then middle-ranking indie four-piece from Colchester - that'll be Blur then - and an Oxford band who had just released their debut album. They went by the name of Radiohead.
"We were watching them from the wings once," Bissett recalls, "and I said to my drummer band-mate: 'Yeah they're a bit indie-schmindy boy band. I don't think they're going anywhere'." She laughs long and loud at that. "Bear in mind it was Pablo Honey time. They hadn't got to their really interesting stuff."
In the end it was Darlingheart who didn't go anywhere. They signed a six-album deal but recorded only one, the fatefully-titled Serendipity. They never did become big in Japan.
"We got utterly shafted, got into a massive amount of debt and got dumped by the record company," says Bissett. "It was the quintessential rock and roll screw-over. I was left going: 'Sh**, what do I do now? I'm not going to university to study English, I've been driving about in the back of a transit for two years.' So I did two things - I applied to drama college and I applied to do an Open University degree in Third World studies, and I thought: 'I'll do whatever comes up'."
What came up was drama college. Graduating from RSAMD in the late 1990s she worked as what she calls "a jobbing actor" for a decade or so before finally turning her hand to directing. She doesn't regret that schooling in traditional theatre, though.
"It's about knowing the rules before you start tearing them up," she says, "so that when you want to come out and play with the cross-form, you've got a very fundamental knowledge of how drama works."
Then again, she performed her RSAMD graduation piece in the back of a transit van using puppets and a live drummer, with her head freshly shaved for the occasion, so in one sense the theatre she's making now has simply come full circle. But what was it that finally made her take the leap from actor to director?
In part it was boredom with straight acting, she says. "I was being told to move there, do that, say this. I thought: 'That's not enough for me'." But it was also born out of a desire "to give voice to under-represented people", as she puts it, something that came out of the volunteer work she'd been doing with various Glasgow charities and activist groups involved in women's issues, and with Ankur Productions, a Glasgow-based theatre company which supports black, Asian and minority ethnic arts in Scotland.
"It was a mixture of being frustrated with the acting itself and feeling that I wanted to grapple with stuff that really mattered to me," she says. "And, possibly, because in my personal life I'd been in a very controlling relationship and I think I came screaming out of that. Maybe that was it. Maybe I empathised with trapped women on a very visceral level and maybe I wanted to give voice to other women. Yeah, I think all those things kind of collided in one big explosion - and the upshot was Roadkill."
Some explosion. Roadkill won Bissett an Olivier Award and a Herald Angel, as well as a Best Production nod from the Critics' Awards for Theatre in Scotland. Actress Mercy Ojelade took a clutch of Best Actress awards too. Since then, the play has toured internationally and in June last year it had its American premiere ... in an apartment in Brooklyn.
Roadkill has travelled far and may still travel further but its genesis lies in Bissett's own Glasgow home. It was her involvement with a charity which gives asylum seekers somewhere to stay while their claim is processed that caused the story to drop into her living room - quite literally. One young woman would have such bad nightmares that she would wake screaming in the night.
"I'd go running through and she'd tell me what was in them," Bissett recalls. "She had crashed into my world, so I thought that was what I wanted to emulate. She'd come into my living room, so I wanted to take the audience into hers."
It made for a powerful and provocative work. "People were in her world, colluding with her world, physically trapped in it with her. And I could see the impact that was having on them."
It was Roadkill which launched Bissett's own theatre company and if there was any doubt about the sorts of stories she and it were going to be drawn to, the company name dispelled them: Pachamama Productions, named for the Aztec goddess of fertility. "There's a few different wine companies with the same name, as I later discovered," she laughs, "but she's a strong female figure."
It's tempting to make the same claim for Bissett, though that strength manifests itself in unusual ways. In her approach to directing, for instance, which is collegiate rather than dictatorial. "Everyone has a voice in my room because they all bring something to it," she agrees. "I have a very open way of working, which is that anybody can pitch in. I'll still be the one steering the ship and I'll give all these ideas space and then decide which way we're going. But I think there's something very exciting about people jamming, and that comes from having being in bands."
So she's a facilitator, then, someone who isn't too worried about territory or maintaining control. That is, I venture, a female quality ...
"Maybe," she says. "Possibly. I'd be cautious about labelling it an exclusively feminine quality because I've worked with male directors who work in a similar way."
GRIT has yet to open to the public but as we talk it's clear Bissett is already thinking ahead, chewing over the ideas and subjects that might emerge in her next project. She has mentioned Kirsty Wark's recent TV documentary Blurred Lines: The New Battle Of The Sexes, and from that spun off into a diatribe against computer game Grand Theft Auto, in which players can not only use prostitutes but murder them afterwards in order to get their money back.
"OK, boys shooting each other up with guns, it's probably going to happen, I've seen that with my nephews. It's hard-wired, so I get that," she says. "But when did jumping on a prostitute's back and calling her a bitch become OK? The big shock-horror stories are one thing, but it's the stuff that happens every day that makes you go, 'This is not cool. How can we accept that that's just an everyday way that men and women relate to each other?'"
So is this what her next piece of theatre is going to be about? Drawn in by her passion, I'm already imaging a site-specific work - a car park, perhaps? - with backdrops flashing up computer games visuals.
"Well," she says, drawing out the word as she decides how non-committal she's going to be. "There might be a strand of it in there. There is a thought in my head. Yeah, I think once your eyes start opening you see there's still a lot to be discussed and questioned."
If it happens, it'll be fascinating to see how the conversation goes and what the answers look like with Cora Bissett doing the asking.