A melting pot of spices

'Chiang Mai people love gaeng hang lay too much!' laughs Yousubfee Aimwathana. Seated at the back of Pawn Poon spice shop, on a narrow lane in busy Muang Mai market, he and his brother Subbin - Pawn Poon's owner - are talking about hang lay curry ('gaeng' is Thai for 'curry'), a beloved dish in the northern Thai city. Rich and meaty, lush with fragrant dried spices, soured with tamarind and spiced with plenty of fresh ginger, gaeng hang lay is to Chiang Mai natives what gaeng keow wan (green curry) is to Bangkok people. 'It's northern food, Chiang Mai food, real local food,' says Subbin.

Much like the Thai-Indian Aimwathana brothers themselves, gaeng hang lay is a fusionist expression of Chiang Mai's trading past. The city sprawls from both banks of the Ping River. In the 19th and early 20th centuries its port in the Gat Luang neighbourhood, Chiang Mai's original commercial core, bustled with boats from Bangkok loaded with goods and teak logs. Chiang Mai was a stop on a land route through Myanmar, Thailand and Laos plied by Chinese Muslim traders from Yunnan, and a launching point for overland caravans to the southern Myanmese port of Moulmein.

As a result Chiang Mai became home to migrants from as far away as India. Some 90 years ago Subbin and Yousubfee's father arrived from his village near Mumbai with a throng of relatives. By that time Gat Luang's textile trade was dominated by Indian immigrants; the young Farkaruddin Sethjiwala broke ranks and opened Chiang Mai's first shop selling dried spices imported from India and Indonesia.

Those spices found their way into what is probably gaeng hang lay's predecessor: a mild Myanmese meat curry that might have made its way to Chiang Mai with the Shan ethnic minority (also called Tai Yai), many of whom came to the city to work for British logging companies in the late 19th and early 20th centuries. Author and photographer Naomi Duguid, who spent six months in Myanmar gathering recipes for her forthcoming cookbook Rivers of Flavor, notes that Shan stews and curries and gaeng hang lay share ingredients such as shallots and powdered turmeric. They are prepared similarly: meat, spice paste and other ingredients are placed in a pot and cooked together until oil rises to the dish's surface. In central and southern Thailand, by contrast, spice pastes are fried separately in oil or with coconut milk, while most northern Thai-style curry recipes require paste to be boiled separately in water or broth before meat is added.

As further suggestion that gaeng hang lay is Myanmese in origin, Duguid points to a recipe for pork curry in the 2004 book Introduction to Myanmar Cuisine by Ma Thanegi. Called wet tha hin lay ('wet tha hin' is Myanmese for 'pork curry'), the dish includes shrimp paste - a component of the spice paste for most versions - and roselle leaves, a common souring agent in Myanmese cuisine. As a substitute for the latter the author suggests green mango, wild plum or tamarind, the ingredient used to sour Chiang Mai's gaeng hang lay.

It's not far-fetched to imagine Yousubfee and Subbin's northern Thai mother or another adventurous Chiang Mai cook raiding Gat Luang's Indian spice shops to add a little zing to Myanmese wet tha hin. Khao soi, Chiang Mai's iconic curry noodle soup, also incorporates a range of spices more often associated with southern Asia than with northern Thailand, as does laab khua, a northern dish of chopped fish, pork or beef sauteed with chillies, prickly ash, an array of dried spices and chopped fresh herbs. Duguid notes the subcontinent's influence on Thai cuisine is seen elsewhere as well: southern Thailand's meat-and-potato gaeng massaman mimics Indian yellow curries, and in northern Thai dialect the word for potato is not man farang (Thai) but aloo, as in Myanmar and parts of India.