It is 8pm on a Friday night and the upbeat weekend vibes are in full swing at Mexican bar and restaurant Super Loco at Customs House.

Spilling into the outdoor area of the breezy bar and restaurant is an after-work crowd that is celebrating the end of the work week with a cocktail in hand. Inside, the restaurant is buzzing with chatter and the tables are laden with all manner of tacos and quesadillas that are priced at $16 and under.

Just two months old, the alfresco-style joint, which directly overlooks Marina Bay, is already drawing crowds.

The brains behind this popular joint are Australian brothers Julian and Christian Tan, co-owners of The Loco Group of Mexican restaurants in Singapore that includes Lucha Loco in Duxton Hill and Super Loco in Robertson Quay.

The brothers have no more than a decade of hands-on experience as food-and-beverage entrepreneurs in Singapore, but their instincts as savvy businessmen and their knack for putting customers first have helped them carve out a niche in the competitive dining scene.

Christian, 46, who used to work in the IT business, says: "For us, it has always been about creating places that we want to visit as patrons - spaces that feel friendly, upbeat and suit groups of people coming together."

It was with this in mind that they started Lucha Loco together in 2012 with one other partner, Ajay Parag.

Last year, their consulting chef, Jason Jones from the famed Melbourne Mexican restaurant Mamasita, joined the business as the fourth partner.

Christian, who is the older and quieter of the two brothers, says: "We were looking to move away from the Americanised Tex-Mex joints that Singapore had and create a space that felt honest to the many traditional Mexican restaurants we had visited on our travels to the country."

He adds: "We knew that we didn't want to play on any stereotypes and have sombreros and donkeys on the walls."

To put out a restaurant they could be proud of, the brothers - born in Perth to an Australian mother and Malaysian-Chinese father - made study trips to Mexico to gain knowledge about tequila and the country's myriad street food offerings, as well as gather inspiration for their restaurant's menu.

"We even connected with the Mexican ambassador in Singapore, who put us in touch with businesses in Mexico that we were able to visit and learn from," says Julian, 44, a Singapore permanent resident and commerce graduate from the University of Western Australia, who previously worked in investment banking.

The brothers' attention to detail is seen, for example, in how they import numerous ingredients and food products directly from Mexico, including the corn flour the restaurants use for their tortillas.

The restaurants also offer a taste of Mexico by dedicating four pages of their drinks menu to more than 80 different mezcal and tequila options, including Fuenteseca, a rare tequila that is aged for 18 years.

Their earnest approach to running the business seems to have paid off. The first international outlet of Super Loco is slated to open in Jakarta in January.

For the two mid-career restaurateurs, their venture into the food- and-beverage business began in 2004, with the younger brother first taking the lead.

Julian, who was then working in Singapore in investment banking, had decided to invest in the rooftop bar Loof at Odeon Towers with three partners.

He had no plans to leave his day job, but the bar's success, given that it was among the first alfresco rooftop bars in Singapore, made him reconsider his career in finance.

His keenness to enter the food business rubbed off on Christian, who was then working for an American IT firm and often travelled to Singapore for business.

"In between seeing Loof succeed and the both of us facing corporate burnout, it felt like the right decision to try our hand at something completely different, even though our parents were obviously not too pleased with our decision to quit our jobs," says Christian, who graduated with a marketing degree from Edith Cowen University.

Their mother works in the airline industry and their father works in property.

They have a younger brother, Eugene, 42, who is an ocean photographer in Australia.

Hands-on approach to success

The opportunity for Julian and Christian to make a career switch came in 2009, when they decided to team up with Julian's partners from Loof to launch the 10,000 sq ft Tanjong Beach Club in Sentosa.

Inspired by world-class beach clubs in places such as Bali and Miami, the $4-million project opened its doors after 10 months of construction, with a party for 2,000 people in May 2010.

"We put everything on the line - all our savings and all our effort and time," says Christian.

"We were there every day, learning from the architects and contractors and tweaking the menu along the way.

"It was quite nerve-racking on opening night, when we were inundated by customers and our point- of-sales system went down; complete chaos - but in a good way."

The opening night hiccup did nothing to turn away beach-club lovers.

Six years on, Tanjong Beach Club continues to draw more than 2,000 people over the weekend.

Spurred by the success of their business venture, the brothers decided to strike out on their own in 2012.

They saw a gap in the market for casual, lively dining and watering holes that offer people a place to get their party started early, and they settled on a scrappy shophouse in Duxton Hill.

With $600,000, they opened Lucha Loco in May 2012.

The restaurant's name and branding are inspired by Mexican professional wrestling, which is known as lucha libre.

Determined to make it work, the brothers ran the business with a hands-on approach; at least one of them was there every night to man tables, run the cash register or sling drinks.

Four years on, the restaurant remains packed every night with a good-looking crowd - mostly young corporate types looking to unwind after a day's work.

Regular customer and Mexican expatriate Margarita Carmen, 39, who is a housewife, says: "They don't pass off gimmicky decor and inauthentic, Westernised food as Mexican. It has good flavours, an excellent tequila selection and genuinely friendly service. The party always feels like it's in full swing at Lucha Loco."

The partners opened a second restaurant, Super Loco, in Roberston Quay in 2014 and made it more family-friendly, in line with its residential neighbourhood, by offering a wider brunch menu.

Its latest outlet at Customs House opened in September and the team continues to be involved in the restaurants' day-to-day operations.

With their first international Super Loco outlet opening, they plan to shuttle between the two cities monthly.

The restaurant in Jakarta is a partnership with the Union Group of restaurants, which operates a chain of upmarket eateries in Indonesia.

Julian says: "To be able to take our brand to new markets and still be so hands-on is something we're both really proud of.

"And to see the business succeed so organically and our customers just enjoying themselves at our restaurants has been one of the most rewarding things for us."

Julian on Christian: He is a friend and role model

For Julian Tan, 44, his older brother Christian, 46, has always been both a friend and role model.

He says: "Given our small age gap, we got along really well as kids and it's something that continues today. We have a very close relationship and I trust his opinion more than anything."

Not only did they grow up playing together, but they also worked on odd- jobs together, from selling lemonade and mulberries at the ages of 10 and 12 to washing cars and working the tables at restaurants and bars as teenagers.

He says: "Whatever odd job Christian was doing, our younger brother Eugene and I were likely to follow suit quickly."

It was heartening for him, therefore, to see the trust he had in his older brother reciprocated when Christian left a well-paying job at an American IT firm to join him in starting Tanjong Beach Club and, later, their own group of Mexican restaurants.

Julian says: "I might have been the one to start the ball rolling, but I'm really glad Christian trusted me enough to take the leap together and put everything on the line. I don't think I could have done any of this without him.

"It's been a steep and sometimes overwhelming learning curve, but it helps to know that we have each other's back, no matter what happens."

He is especially thankful, he says, for his brother's company on stressful nights, when the restaurants are packed. That brotherly bond is crucial, he believes, when it comes to working with family.

"When you're working with a sibling, you're able to be brutally honest and know that they won't take it personally."

Christian on Julian: He is calm when things go wrong

In the seven years that they have worked together on high-pressure food-and-beverage projects, the Tan brothers have had nary a dramatic shouting match.

The secret to their comfortable working relationship? Julian's level-headed nature, says Christian.

"He's the sort who is excellent at problem-solving and asks the right questions. He has an ability to think clearly about a situation without forcing his opinion on anyone else."

It helps too that they do not cross each other's areas of responsibility and, when they disagree on certain business issues, "the person who feels most passionately about the issue takes the lead", says Christian.

Christian handles marketing, social media and guest experience, while Julian takes care of finance and business development.

Their other partners, Ajay Parag and chef Jason Jones, oversee operations, human resources and the kitchen.

"Keeping our areas of responsibilities distinct has allowed Julian and I to always talk things out and have healthy discussions instead of big blowouts," says Christian. "It also helps that he is extremely calm and rarely panics, even when several things are going wrong at the same time."

The brothers - who are both in relationships - continue to enjoy each other's company outside of work.

They live in apartments across from each other in Sentosa Cove and spend their free time travelling and surfing together.

"We're lucky that we have similar personalities and goals, but when it comes to personal strengths, we are different but complementary," says Christian.