The film has dazzling action scenes, dodgy gangsters and erotic dancers as its protagonists, and a pumping soundtrack to boot. Yu had more than 80 people at his disposal when he shot it in Sao Paulo - a far cry from the skeleton crews he used in the past.

The film revolves around Yuda (played by Anthony Wong Chau-sang) and his adopted son Kirin (Japanese actor Joe Odagiri), who run a lucrative business in the city's black market. Their shady business empire begins to crumble, however, when corrupt officials and underworld kingpins start pressing for a share of their profits and power; their gradual downfall forces both father and son to face up to their destinies.

Yu says the film was inspired by the real-life story of Law Kin-chong, a Chinese gangster who was brought to heel by the Brazilian police after his failed attempt to bribe officials.

'While most people think he's a greedy triad boss, I'm interested in how isolated he was by the absurd socio-economic system around him,' he says. 'He built his empire from scratch and had to rely on corrupt bureaucrats and locals to support his business. His power is fragile.'

Sao Paulo's chaotic urban landscape was very much like Hong Kong in the 1960s and 70s, Yu says, a time when Hong Kong was riven with social problems before the economy took off. 'I had a feeling of deja vu when I first went there,' he says. 'But the culture and people are so different from Hong Kong.'

Central to the film, Yu says, is the contrast between the introversion of his Asian protagonists and the raw expressiveness of their Brazilian counterparts. 'I'm interested in seeing how Asians survive in this city of unadulterated violence,' he says. Cultural dislocation is a recurring theme in Yu's films. The alienation felt by Yuda and Kirin in Plastic City is also present in Love Will Tear Us Apart, in which a mainland woman struggles to adapt to life in Hong Kong, and in All Tomorrow's Parties, in which two siblings try to rebuild their lives in a deserted city after being freed from a labour camp in a fictional 21st-century authoritarian state.

'It's not just a geographical home, but a psychological one. It's the search for a home within a person that interests me,' says Yu, adding that this fascination with roots stems from identity issues he sees as being common among Hongkongers. 'People of my generation have a lot of uncertainties about identity.'

Yu's parents were intellectuals who graduated from Jinan University in Guangzhou, but ended up running a farm in Sheung Shui in the New Territories. In the late 80s, Yu and his family emigrated to Canada.

Yu began his career as an advertising executive, but was so inspired by Robert Bresson's Pickpocket that he quit his job and moved to Brussels to undertake a cinematography course at the Institut National Superieur des Arts du Spectacle. 'I chose cinematography because it's a more practical subject. I think you should learn directing by doing it rather than just studying it,' he says.

He returned to Hong Kong in 1994 and worked as a freelance cinematographer for local sexploitation films.

In 1996, he made his directorial debut in Neon Goddesses, a 45-minute documentary about three young women dreaming of success while working in Beijing nightclubs. The film earned him the grand prize at the second Hong Kong Independent Film and Video Awards (IFVA), as well as a jury award at the Marseilles Festival of Documentary Films.

It was around that time that he met Jia, who came to prominence when his first film, Xiao Shan Going Home, won the IFVA's grand prize in 1997. Yu has since worked on all Jia's full-length features, from Xiao Wu (1997) to 24 City (2008). 'We share a similar ideology in filmmaking. We don't need much time to discuss what we want,' says Yu.

While Yu has shot all Jia's films, Jia has produced all of Yu's directorial efforts, starting with Love Will Tear Us Apart, a film made possible only after Tony Leung Ka-fai waived his fee to star in it. The film competed for the Palme d'Or at the Cannes Film Festival and propelled Yu to recognition.

The success of this film prompted French production company Celluloid Dreams to finance his next project, All Tomorrow's Parties. Again, Yu went to Cannes with the film, which featured at the festival's Un Certain Regard competition.

Yu says his path of making films independently is driven more by necessity than choice. 'When the mainstream film industry is experiencing a downturn, filmmakers must take the initiative and produce films independently to survive,' he says.

When the industry picked up again last year, independent filmmakers went searching for more commercially driven projects. 'We need a larger audience - and it's vital to make films that are more accessible,' he says.

Plastic City received mixed reviews when it premiered at the Venice Film Festival last August, with critics calling it confusing and pretentious.

Yu says he was not satisfied with the version shown in Italy, saying it was rushed to meet the festival deadline. He has since reworked the film, cutting it by 30 minutes. 'It's more polished,' he says.

Yu says he's more than happy to work on the mainland - so much so that he stays in hotels when he returns to Hong Kong for work or meetings. 'There's a great potential in mainland [Chinese] cinema. Collaborating with mainland filmmakers and companies will be the [dominant] trend,' says Yu.

'Also, I can't stand the passivity of Hong Kong people,' he says, yawning.

Plastic City opens today