'We're always willing to tell people about how our dishes are made,' says Dr Daniel Chui, executive director of Fook Lam Moon, or 'tycoons' canteen' as it's sometimes known. 'It's just that people take shortcuts nowadays.'

Dishes such as eight treasure duck (which, more often than not must be ordered in advance at other establishments) are favourites at Chui's restaurant.

These dishes are often laborious to make. They require good knife skills, and meticulous preparation including extensive cleaning, delicate handling and long marination and cooking times.

Classic techniques are difficult to honour under the pressures of time and cost. Restaurants are taking shortcuts or deleting elaborate dishes from menus. If they are offered, mass-market food outlets bank on customers not knowing the difference between a properly made version and one that is hastily prepared.

Chui cites economic reasons for the decline of traditional dishes. 'Customers expect the prices to stay low despite rising food costs and rents. So naturally the restaurants have to cut costs somehow,' he says. So how does he do it? 'We're lucky that we own all the properties where our restaurants are located, which gives us a bit more breathing space.'

According to Lau Shing, chef supervisor at Fook Lam Moon, eight treasure duck is made by stuffing a duck with a combination of lotus seeds, lotus petals, barley, dried shitake mushrooms, salted egg yolk and gingko. These ingredients are relatively easy to find in most Chinese larders.

But the restaurant must ensure that it is able to procure the best. That means lotus seeds that soften after slow cooking, rather than harden, for example. The duck needs to be carefully cut open, deep-fried, stuffed, sewn back together, then finally braised for around two hours.

The ingredients that go into the dish were never particularly expensive. Outlets popular with the working class, such as Lin Heung Lau, have always served it. Its decline has more to do with the labour involved. Lau mentions a similar, but lesser-known dish, ba wong ngaap, or the overlord's duck. 'Not many people make it nowadays,' he says. This is because it's even more complicated, with the additional step of having to debone the bird prior to stuffing. (In this case, it is stuffed with glutinous rice rather than barley).

When done by the masters, the deboning and stuffing are completed through a small incision at the base of the duck's neck, so the bird doesn't need to be opened and sewn back up. The neck is simply tied in a knot to seal the stuffing. 'It takes some practice, but it's not particularly hard. It's just that not everybody can be bothered to go through all the steps,' says Lau. 'It takes a lot of time and manpower just to do one dish, as it's fiddly.'

The shortcuts include products that can now be made in factories, such as cheung fun (rice paper rolls).

'Shortcuts are a very common problem nowadays,' says Lau Chun, a food columnist. He's also the son of Lau Kin-wai, who owns Kin's Kitchen, and private kitchens Kin's Terrace and Yellow Door Kitchen. In many restaurants, the popular Cantonese dish salt-baked chicken 'is not really baked in salt that's been heated up in a hot wok, like it's supposed to be', says Lau Chun. 'They just use a brine instead to make the chicken salty.'

Each chicken needs a least 30 minutes on the stove, which is 'not something larger Chinese restaurants that need to serve more than 100 people with two or three stovetops can afford to do', says Lau. Out of the chain, it is only served at Kin's Terrace, where menus are pre-arranged.

'It might not be a matter of whether there are people who know how to do it,' says Leung Man-to, director of Tai Wing Wah restaurant in Yuen Long, which is known for Hakka food from the walled villages in Hong Kong.

Leung cites fish dumplings, a popular Shun Tak offering: 'If you make it by hand, you need to fillet the fish, take the flesh and incorporate it into the dumpling wrapper, then use more of the fish, and beat it to a paste for the filling.'

These steps are often mechanised nowadays. The result is, Leung says, that 'the flavours and textures are not the same'.

Leung often travels to cities in Guangdong to find old dishes. These include dishes like mud carp belly steamed with shrimp paste. This requires all the bones to be removed, with only a minimal amount of flesh lost in the process. Seemingly simple dishes such as stir-fried bean shoots with minced pork, served in lettuce cups, are also dropping off menus.

'You have to choose the right bean shoots, and pre-cook them to get rid of the raw, grassy scent,' says Leung. 'I wouldn't say that no one in Hong Kong knows how to make these dishes, but they take a lot of effort and the margins are low. So who still has the patience?'

Leung adds that people are counting cents and find it hard to be passionate about these techniques.

At the much-lauded Shung Hing Chiu Chow Seafood Restaurant chive pastries filled with crab are another hard to find favourite. Making these diminutive bites is no easy feat. Everything from the pastry to the filling is made in the kitchens.

The pastry can't be used for any other dish, because it incorporates fresh chive juice, which is pressed on site. The filling consists mostly of crab meat, which needs to be carefully removed from the shell.

Another of the restaurant's dishes, marinated mantis shrimp, served raw, doesn't look as though a lot of work has gone into it. But the saltiness of the brine has a distinctive sweet fragrance. The subtle scent comes from Chinese rose wine, distilled from rose petals.

The mantis shrimp are left to soak in distilled water for 20 minutes, before marinating in a mixture of rose wine and rock salt for half an hour. Then they have their heads removed and are butterflied, ready for a final eight-hour marination. 'I don't think many people make this any more, it's too troublesome,' says Shung Hing owner Suen Suk-keung.