Aktar Islam, a winner of BBC2’s Great British Menu, tells Richard McComb about the far-flung inspiration for his curried sea bass.

There’s a bloke with a fried fish stall on a beach on the south-west coast of India. He’s an unheralded cooking star.

His table is laden with mackerel and pomfret, freshly plundered from the ocean. Little does he know he is the inspiration for a fish dish served at a televised banquet thousands of miles away in London.

Aktar Islam, chef director of Birmingham’s Lasan restaurant, revealed how the fare being fried at the modest beach stall captured his imagination and gave him the idea for the sea bass course that was judged the nation’s best fish dish by the judges of BBC2’s Great British Menu.

Millions of viewers watched Aktar prepare his spicy Keralan sea bass with soft-shelled crab and green mango chutney for the People’s Banquet at Leadenhall market.

The 32-year-old chef cooked the dish for 100 specially invited guests after winning the Great British Menu’s Central region heat and then taking top spot nationally for his fish course.

The core ingredients for the bass’s marinade are kokum, tamarind and chilli and Aktar revealed how the combination caught his eye during a trip to India with Lasan founder Jabbar Khan in 2009.

He spotted a waterfront stall-holder cooking with the marinade at Cochin, where families from all backgrounds descend on the beach for their evening meal.

Aktar says: “You have people who don’t have footwear because they are so poor and you have people pulling up in Bentleys and Rolls-Royces eating the same food. I thought it fitted perfectly with the brief for a people’s banquet.”

The chef loved the combination of kokum, an Indian dried fruit he describes as having a “smoky, earthy” flavour, with tamarind and chilli.

It sowed a seed in his culinary brain for a new marinade to which he added onion, curry leaves, garlic, star anise, mustard seeds, coconut oil ... The list kind of goes on.

Aktar then added a final flourish, introducing soft-shelled crab and a raw green mango chutney. Thus was the idea for Aktar’s fish dish born.

He decided to use sea bass as a special occasion fish and the flesh was steamed rather than fried to give a more intense flavour to the marinade.

Aktar loves the idea of modifying Indian street food and the results impressed the judges of the Great British Menu as well as Brummie chef/mentor Glynn Purnell.

(Purnell, of course, is a two-time winner of Great British Menu, including victory for a dish of masala monkfish. It means Birmingham has twice won the BBC contest for curried fish – not bad for a landlocked city.)

“I like simple recipes that housewives do at home. What we do is deconstruct the dishes and make them better.