Ella Walker meets Dishoom's executive chef Naved Nasir, who lets her into the kitchen as the restaurant celebrates its debut cookbook.

I am very much in the way. This is instantly clear.

The chefs at Dishoom Kensington - their whites pristine as they to and fro with huge trays of buns to be stuffed with keema and paneer - dance skilfully between charcoal grills and sturdy metal pots the size of car tyres.

But now they also have to contend with me, attuned only to the prawn moilee (a south Indian style curry) under my nose, and not the intricacies of a frenetic open kitchen.

I'm here with Dishoom executive chef Naved Nasir, one third of the team behind the restaurant chain and its debut cookbook, Dishoom: From Bombay With Love.

The other two thirds are co-founders Shamil Thakrar and Kavi Thakrar, who launched Dishoom in 2010.

They opened first in Covent Garden, and now have five restaurants in London (including their labyrinthine Granary Square space, where you can lose all sense of time as the cups of chai keep coming), as well as joints in Edinburgh and Manchester.

Inspiration initially sprung from Bombay's beloved Irani cafes, and "each Dishoom is a small love letter to these cafes in Bombay", as Nasir explains over bowls of crisp, rust-coloured okra fries and knubbly bites of chilli chicken.

The cafes are the legacy of Zoroastrian immigrants from Iran, who set up these cosmopolitan nooks in the early 20th century, which, as a by-product of savvy business acumen (communal tables designed to optimise space) made India's caste and class systems inconsequential - or at least suspended them for a meal and a drink or two.

"[You'd] share a table - the chair is yours," says Nasir. "These cafes broke down those barriers. That for me was the biggest contribution these cafes had, that you could have a Muslim sitting next to a Hindu or a Sikh, and a Christian next to them."

From 400 or so scattered across Bombay, they are now barely 30 of these opulent, nostalgically tattered Irani cafes left.

While Dishoom is a love letter, it's not an exact replica. And neither are the dishes you'll find on its menu or in the cookbook - these aren't traditional recipes done to the authentic letter.

Instead, Nasir's ethos is to ask: "If you tell someone in Bombay about a bacon sandwich, how would he go about it?" The answer is Dishoom's famed tomato-chilli jam and cream cheese-slicked bacon naan roll.

But perhaps their most lauded, signature dish is the house black daal. It's beside the prawn moilee we're making, majestic and statuesque in its colossal pot, quietly deepening in flavour.

"You can tell the feeling of the kitchen by the daal," says Nasir, ominously explaining that you mustn't scrape the crust at the bottom of the daal pan with the lip of the wide ladle that sits in it, or the smoky burnt flavours diffuse into the grains. Instead, you stir and scrape down the sides of the pan with the rounded base of it. It's a system you don't mess with, so no, I don't get a go.

Interestingly, daal may seem a simple exercise in comforting bowl food - it's got very few ingredients and is arguably quite plain - but it's far more intricate than you might imagine.

It can be so sensitive in fact; when Dishoom opened in Manchester, their head chef there couldn't get the house special quite right, no matter how hard she tried. Then they realised: "The water in Manchester is not as hard as the water in London, that had an impact on the urad daal grain as to how it cooks."

Against the jazz sax pumping through the speakers and the clatter of cups frothing with rose and cardamom lassi the colour of pink Angel Delight, Nasir recalls how, as a young chef in India, it took him six months to piece together his then restaurant's daal recipe. Although, he was somewhat hampered by his secretive superiors.

Sharing recipes is important though, he notes: "If you're too secretive, recipes will die."

And so he's quite happy to share the secrets to his perfect, fragrant prawn moilee - a dish that was a special at Dishoom Covent Garden. It turns out sunshine-yellow, the prawns plump and taut against our teeth, and the thick half-moons of white onion we chucked in have broken down and leaked their sweetness ("Browning up onions is a very critical stage," Nasir reminds me).

We eat it with steamed rice and wedges of lemon, and feel a little more like we're in Bombay than we did before.

Dishoom: From Bombay With Love by Shamil Thakrar, Kavi Thakrar and Naved Nasir, £26.