Its plays, including Kiss the Fish, Guru of Chai and Krishnan's Dairy, have seen them regularly touring Britain, the United States, India, Germany, Singapore, Australia and, of course, New Zealand.
So Rajan sat through The Elephant Thief's opening night and admits it was tough because he kept seeing things he might have done differently.
"And then I looked at and listened to the audience, who were all laughing and having a great time, and realised my perception is flawed, my expectations unrealistic and I was a cramped-up mess when it was all actually going well," he says.
"When I relaxed, I loved it and to see the actors doing what actors are meant to do, taking your words and making them come to life and working as an ensemble, was fantastic."
He acknowledges it feels strange not to be on stage, but doesn't feel any sense of loss: "It's not as if I'll never do it again. I'm doing Guru of Chai in Canada and Krishnan's Dairy in India later this year."
Then there's the not-so-small matter of being asked to write a play for California's South Coast Repertory, one of the USA's largest commissioners of new theatre work.
Lewis and Rajan started with one of their former shows, The Dentist's Chair, but say it's morphing into something new and different with more of a US sensibility and the working title Welcome to the Murder House.
They'll visit South Coast in July to talk more about the project, then South Coast representatives will visit New Zealand in December for a preview.
"If they like it, it goes on to the programme for the beginning of 2018 and if not, well, we do a bit more work," says Lewis.
And the script for the long-awaited film of Krishnan's Dairy is finished; the play, Indian Ink's first, premiered in 1997 and led to two sequels, The Candlestick Maker and The Pickle King.
Meanwhile, they are putting their energy into ensuring The Elephant Thief has a successful season. Lewis says it helps that they've "handed things over" to actors they trust and that two, Nisha Madhan and Julia Croft, have worked with Indian Ink before.
David Ward, who's collaborated with the company for more than 10 years, is musical director and composer, while the script itself is replete with the heightened theatricality and lines that prompt "the serious laugh" Indian Ink is known for.
The serious laugh? It's the ability to make the audience chortle and then reflect on deeper themes. The Elephant Thief is concerned with extinction - not just of flora and fauna, but the human race itself. Yes, there's an elephant in the room - sort of, says Lewis - after all, the idea came from an elephant.
When Lewis and Rajan were in India, touring Guru, they visited an elephant sanctuary and met an elderly mahout who had to see one particular pachyderm daily.
"He was an incredibly vital and alive person, but tiny, and he had the largest elephant of all in his care. He said if he does not go in and see the elephant, the elephant gets depressed, so he can't leave or go away," says Lewis.
"To me, that was such a wonderful, beautiful and tragic story."
They were shocked to hear predictions that elephants will be extinct in the wild in 50 years. So the writing process began and, along with it, the continuing quest to blend comedy and pathos, music and masked characters and tell a "beautiful, funny, sad and true" story. The Elephant Thief has been two years in the making, including a well-received premiere in Hamilton last year.
"The writing process was very different because we had to come to terms with the fact that Jacob was not writing characters for himself," says Lewis. "We had to spend quite a bit more time finding the voices, considering how to get the humour going and keep the story always going forward. We had a lot of fun with some of the lines, but it wasn't going anywhere, so we had to sit down and think more about, 'who's the hero?' and it turned out to be Leela."
The story is set in the future, when India is the most powerful country on Earth, and it follows young Leela Devi who leaves her tribal home to see the world. Unexpectedly, she finds her father's elephant has followed her. As Leela battles corrupt officials, hungry poachers, fanatical leaders and supreme beings, an unlikely love story unfolds and a quiet revolution ferments.
A revolution, of sorts, took place in the rehearsal room when Madhan suggested there could be more female characters. Lewis happily took the suggestion on board and says one woman told him after a performance that it was "an incredibly feminist piece".
Madhan, who appeared in Indian Ink's last show Kiss the Fish, wanted to work again with the company because she enjoyed the process of creating a show with Lewis and Rajan and says the stories they tell are beautiful and unique.
She plays four characters in The Elephant Thief: the Hindu goddess Kali, a police officer, the Prime Minister of India and a woman who believes she's the rightful heir to the French throne.
"It's fun to play Indian women of high status, which is something I'm not used to doing because Indian women characters are often in lower-status roles but here they get to rise above that," she says.
This time round, the masks are simpler - just different sets of false teeth and Madhan says that's enough to transform into entirely different characters because it automatically changes the way you speak. She giggles when asked about reports from co-star Vanessa Kumar (who plays Leela) that the teeth have occasionally popped out "but that's fine because I was able to incorporate it and move on."
As far as newcomer Kumar was concerned, that was a wonderful and genuine "teachable moment" in a process packed with opportunities for the recent drama school graduate.
Kumar met Rajan while studying at Toi Whakaari - the NZ Drama School, and describes the chance to work with him and the company as quite incredible.
"I'm learning that being in a room with people as talented as those I'm working with sometimes makes me feel very nervous but ultimately it's good because it makes me want to match their level," she says. "They have such an ease about them."
And what does she like about the play itself?
"Playing with the cast in character and getting to meet people - the characters - that have been unheard from for so long. Leela is practically an Untouchable, but has drive and power and when you have that you can change the world.
"She's one of the always underestimated."
The cast also includes Jonathon Price and Patrick Carroll.
Performance
What: The Elephant Thief
When and where: Q Theatre, June 15-July 2.
