Visit the birthplace of Tex-Mex for the ultimate tacos, fajitas and burritos

They say everything is bigger in Texas, and the owners of Mi Tierra in San Antonio appear to have taken that as a personal challenge. Waitresses bustle between tables in red, white and green uniforms that are at least 80 per cent frills as they deliver fishbowl-sized margaritas and trays laden with stuffed poblano peppers, sizzling fajitas and tacos overflowing onto mountains of rice and beans.

In one corner is an altar with a giant painting of Selena, the singer known as the "Mexican Madonna", and a soundtrack of peppy, horn-laden music is barely audible above the clamour of 600 diners clad in everything from cowboy hats to quinceaera dresses.

In the foyer out front, families greet each other in a mix of Spanish and English as they hungrily eye cabinets filled with Mexican sweets including glistening candied yams, pumpkin-filled empanadas and crispy sopapillas dusted with cinnamon and sugar. That this scene remains largely unchanged from breakfast service until midnight is a testament to the deep passion San Antonians have for their native Tex-Mex cuisine.

Some xenophobic politicians would have you believe that the Rio Grande has always provided a barrier between two distinct cultures. In truth, the porous border has provided little impediment to the development of a thriving transnational culture. And as is so often the case, food has been one of the most effective vehicles for cross-cultural communication.

"This area of Texas was part of Mexico before it joined the United States," explains Diana Barrios-Trevino, who co-owns the sprawling Los Barrios restaurant in the city's northern suburbs. "When vaqueros - the Mexican cowboys - would ride up here, they brought dried chilies to add to their cooking and soon the other cowboys began to notice that their food tasted much better."

After becoming part of the US in 1845, San Antonio grew rapidly and local Tejano women set up open air stalls with colourful tablecloths to cater to the cowboys, soldiers and workers who flocked to the city. In the plaza next to San Fernando Cathedral, these "Chili Queens" prepared tamales, enchiladas and large pots of meat seasoned with a pungent mix of garlic, peppers, onions and cumin: the original chilli con carne.

Once railroads connected the city to the rest of the country, these stalls became a popular attraction and tourists began bringing the dishes they tasted back home with them. Today you'd have to search far and wide for a diner without hot sauce or a bar that doesn't serve margaritas, and the city where it all started is one of only two UNESCO Cities of Gastronomy in the USA.

Described by Netflix's Taco Chronicles as "the cradle of Mexican food in the US", San Antonio has long welcomed immigrants from all across Mexico. That's unsurprising when you consider that for centuries this was primarily a Hispanic region, first as part of colonial Spain, then as the capital of the Mexican province of Tejas.

Fittingly, many local Tex-Mex venues acknowledge the varied regional styles that comprise Mexican cuisine. William Cortez's great-grandfather opened Mi Tierra as a three-table cafe after emigrating from Guadalajara in 1941, and while he would struggle to recognise the venue in its current form, many of the dishes remain largely unchanged.

"As you travel through Mexico, each region has its own specialty and some of those recipes haven't changed in 50 years," Cortez explains. The more traditional dishes - what locals refer to as "interior Mexican" - include mole poblano, Sonoran ribs and tender cabrito (baby goat), and are especially popular with first-generation immigrants yearning for a taste of home. "But when people from all those regions came to Texas the different styles came together in a huge fusion - that's Tex-Mex."

Other dishes draw more liberally from the northern side of the border, including a memorable local hangover cure. Barbacoa and Big Red is an unlikely combination of creaming soda and tortillas packed with onions, salsa and succulent shredded beef cheeks that have been marinated in spices and cooked overnight, but it's a favourite both at family cookouts and many local restaurants. "It's especially popular on weekend mornings to cure you after a big night out," says local food blogger Alexis Serna. "When you pair the nice fatty barbacoa with an ice cold Big Red... it doesn't get any better than that!"

"Visiting Mi Tierra is like a rite of passage. It's a Tex-Mex icon, so everyone has to go there at least once," says Serna, but there are plenty of other places to check out - some locals claim that there are as many as 800 Tex-Mex restaurants spread across the city.

At Los Barrios, which has been serving "comfort food at its finest" since 1979, cross-border classics like enchiladas sit alongside "interior" dishes including menudo and barbacoa. "Tex-Mex isn't just fajitas and burritos," declares Barrios-Trevino; "sometimes you need to include the 'Mex' part as well!" But her most famous dish is a 100 per cent local creation.

"My family didn't invent the puffy taco," she laughs, "but we perfected it." Instead of regular grilled tortillas, discs of masa (dough) are dropped into the deep fryer until they're suitably fluffy, then stuffed with as much meat, beans and guacamole as they can hold. And even at lunchtime, there's only one way to wash them down. "We're in South Texas and it's really warm here," Barrios-Trevino declares gleefully, "so frozen margaritas are perfect."

Far more humble is Maria's Cafe, which looks more like a classic diner than a Tex-Mex joint. Step inside and you'll see six tables groaning under the weight of food with the dial turned all the way up to "comfort". Enchiladas arrive as bright red tortillas wrapped around salty white cheese and hidden beneath thick brown gravy, while smoky barbacoa and brisket tacos peak out from beneath a fried egg and spoonfuls of spicy pico de gallo.

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Elsewhere, there's abundant evidence that Tex-Mex is a living tradition that continues to evolve and crossbreed with other cuisines, including the state's other enduring culinary export. You wouldn't know it to talk to many modern connoisseurs, but Mexican vaqueros were a key element in the evolution of barbecue, and some younger pitmasters are bringing things full circle with their own twist on the genre.

2M Smokehouse promises barbecue "con ganas" (with passion) and every weekend long lines form around the teal building to order piquant brisket rubbed with cumin, coriander, and onion powder and sausage links stuffed with Oaxaca cheese, cilantro, and serrano peppers. Instead of white bread, diners can wrap the meat in tortillas made with beef tallow for extra punch and the sides include salsa and pickled nopales (prickly pear stems) with garlic cloves, bell peppers, and serranos.

Other chefs have looked further afield for inspiration and one of the more unlikely fusions is on display at Stixs & Stone, where Latin classics meet Asian flavours in roasted pork belly tacos topped with sweet and spicy Chinese barbecue sauce and Korean-spiced duck breast with hibiscus and pecan mole. The venue's neon pink tortillas made with Big Red soda instead of water are a particular favourite of Serna, who argues forcefully that, "some people knock Tex-Mex, but it deserves to have a much better reputation. Originally it was a way for immigrants to make affordable food, but that's grown into this beautiful world with all these variations that reach across cultures."

"More than a hundred years after the Chili Queens, Tex-Mex is still evolving," he continues. "And while some people might worry about the culture being appropriated and gentrified, change isn't a bad thing. Chefs who use unorthodox ingredients like arugula and honey are furthering the taco legacy, but there'll always be a place for simple, affordable options because this is meant to be food for the people."

Despite being the seventh largest city in the US, San Antonio's compact centre is easily walkable and remains defiantly low-rise. That's most noticeable in the heart of downtown, where plenty of three- and four-storey buildings flank Texas's holiest site. Founded as the San Antonio de Valero mission in 1718, the Alamo served as a religious hub, hospital, prison and military base before entering Texas history in 1836. Davey Crockett and Jim Bowie were among 200 defenders who held off the thousands-strong Mexican army for 13 days before perishing, their famous last stand helping to inspire the Texan fight for independence.

Today the fort is surrounded by a broad plaza of limestone that glows white in the midday sun, while sprawling live oaks provide welcome shade inside the complex. A range of free exhibits re-create the siege and explain how the city has been shaped by different forces, while the hushed atmosphere in the cool, dark church is more conducive to contemplation.

Head two blocks south and you'll find a decidedly more celebratory mood along the Riverwalk, a touristy but undeniably lovely pedestrian path shaded by tall cypress trees and lined with cafes and bars overlooking the San Antonio River. Almost 25 kilometres of paths link all of the city's major sites including Main Plaza, where a nightly lightshow called San Antonio The Saga turns the imposing gothic revival facade of the nation's oldest cathedral into a canvas for a thoroughly entertaining version of the city's dramatic history.

If you want to pick up a few souvenirs before heading home, head to Market Square where multicoloured papel picado (paper flags) hang side by side with bunting decorated in the stars and stripes. Narrow aisles of stalls are packed with everything from sparkly luchador masks and luridly coloured pinatas to handmade pottery, flower-covered cotton dresses and Mexican vanilla syrup.

Getting there: San Antonio is a two-hour drive from Austin, and you can fly from the east coast of Australia with a single connection in LA (American Airlines, Delta), Dallas (Qantas), Houston or San Francisco (United).

Staying there: At the historic Hotel Gibbs you'll find yourself in the centre of the action. San Antonio's first high-rise building sits right on the edge of the Alamo Plaza and the rooms on the south-east corner let you look right down into the fort. Rooms from $US129 ($194) a night. hotelgibbs.com

Don't miss: While the Alamo is by far the most famous of the five Spanish missions strung along the San Antonio River, the others are less crowded and as a result can be even more evocative. Hire an e-bike to tackle the 13-kilometre trail linking these ornate churches, and make sure to allow plenty of time to enjoy the informative guided talks provided by the rangers.

Explore more: visitsanantonio.com

The writer travelled with assistance from Brand USA and Visit San Antonio.