For Senigaglia, a key selling point to aperitivo, compared with typical happy-hour promotions, is that the bar snacks do not consist of merely 'popcorn, peanuts and potato chips'. At DiVino, he prepares a daily spread of more than 15 different items, including a savoury mix of grissini, cold-cuts, frittata and bruschetta. The entire buffet is free with the purchase of one glass of wine; customers can choose from a selection of 50 wines by the glass.

'We call what's served [during aperitivo], stuzzichino, or bite-sized finger food in Italian,' says Michele Camolei, the chef at Osteria in Tsim Sha Tsui, which began offering aperitivo last month. 'You are not eating to fill your hunger, you are eating to open up your appetite. That's why aperitivo literally means 'opener'.'

Camolei prepares more than 45 items every night to complement the wines, which are marked down to HK$60 a glass during aperitivo time. 'There's a cold buffet with things like olives, marinated anchovies, hams and cheeses. And I also prepare three warm bites for every glass of wine ordered, and that can be a small piece of lasagne, a chicken roulade with vegetables or some fried shrimp,' he says. 'It is a lot easier for a restaurant to find synergies and offer a big aperitivo buffet compared to a bar. We'll always have something to hand out, depending on what's available in the kitchen.'

'I can't think of any time more perfect than now to have aperitivo,' says Tony Paese, restaurant manager of Gvsto in Central. 'It is perfect for this economy, when customers are looking for the most value for their money.' Gvsto, which opened last month, offers a free aperitivo buffet of 35 items on Fridays and Saturdays, and 15 items the rest of the week; it's all you can eat for the price of one drink.

The economics of aperitivo rely largely on the alcohol consumption of customers, but Hongkongers' rather demure drinking habits prove challenging, say the restaurateurs. 'In Milan, the capital of aperitivo, the bars are overflowing with people who finish up the wines by the bottle. Here in Hong Kong, people may order just one glass and that's it,' says Camolei.

Paese says customers at Gvsto's sister restaurant in Rimini, Italy, prefer to order cocktails such as martinis for aperitivo, rather than wine. He says: 'Most people nowadays think you drink fresh wines such as prosecco for aperitivo. But in the early days, people would order cocktails with spirits, like Campari, which contain digestives.' Paese often recommends cocktails to his customers, but more than 80 per cent of them still opt for wine. Even then, it is usually just one glass per customer.

The Lounge at the JW Marriott Hong Kong has added two Italian beers - Moretti and Peroni - to the mix during Thursday aperitivo hours, and both have proven especially popular with Italian expatriates.

Despite the different options on the drinks list, however, aperitivo in Hong Kong is generally not profitable for most restaurants. 'To be honest, I put it down as a cost,' says Senigaglia. 'But really, it's also an investment. In Hong Kong, when people see a queue, everyone wants to come inside. And once you come inside, maybe you'll stay for dinner.' He estimates at least 10 per cent of DiVino's aperitivo customers stay for a full meal. About 20 per cent of Osteria's aperitivo customers become dinner guests as well, and more than 50 per cent do the same at Gvsto. 'It is not about food costs. It's about the whole chemistry of the restaurant, and in that sense, aperitivo is working,' says Camolei.

JW Marriott chef Hector Pliego sees aperitivo as an opportunity to educate customers about Italian food. He says: 'It's a contemporary twist to introduce Italian flavours and ingredients. It shows people that it isn't just about a big plate of pasta covered in a thick tomato sauce with a glass of Chianti.'

Partnering with sponsors such as Italian food supplier il Bel Paese, Pliego set up an olive oil tasting station as part of the aperitivo buffet. There, customers can sample extra virgin olive oils from Liguria, Tuscany and Puglia, as well as an unfiltered version from Sicily that Pliego describes as having the flavour of 'fresh artichoke'.

'Hongkongers are quite familiar with the flavour profiles of aperitivo. It has a lot of similarities with Spanish tapas, which is already very popular. There's Parma ham from San Daniele instead of jamon Iberico from Spain, but both draw heavily from Mediterranean influences,' says Pliego. 'And the 'small bites' trend has been one of the strongest developments in the food world. The modern-day paradox is that people are looking for something more casual, but their palate is becoming more sophisticated. So there is a growing sector of diners who want to graze on gourmet quality food.'

The biggest difference is that aperitivo and tapas are eaten under different social settings, says Paese. The former is 'not intended as a full meal', while the latter is 'a style of eating a full meal', he says.

'You also pay for every order of tapas,' says Camolei, who spent four years in Barcelona. 'You realise that those small bites add up to one large bill.'

Local customers were cautious about fully embracing aperitivo during its early days, seeing the price point as 'too good to be true', says Senigaglia. For DiVino's sister restaurant, Spasso, where local Chinese make up 60 per cent of the clientele, he says, 'it took over a year to get people to adjust. We would put the food out there night after night and nobody would touch it. They were scared even though we explained it was free. Eventually a few would try it, realise it's the real deal and tell their friends about it.'

Nowadays, aperitivo is popular in all three DiVino group restaurants - DiVino, Goccia and Spasso - and more than half of the guests are regulars. The Lounge at the JW Marriott welcomed 100 customers on its first day of offering aperitivo in April, and now about a third of its clientele are repeat customers. Gvsto and Osteria are slowly building up a clientele.

'At the end of the day, it's not about the drinks or the food - it's a real social moment,' says Senigaglia.

'The more people, the merrier,' Camolei agrees. 'Just remember there are no rules to aperitivo. If you want an extra bite of something, I'll give it to you. If 200 people come, and 200 people want an extra bite of something, I will hand those out too.'

DiVino Wine Bar & Restaurant

73 Wyndham St, Central, tel: 2167 8883 Aperitivo: 6pm-8pm - free buffet with purchase of one glass of wine Sample items: grissini with proscuitto, frittata, bruschetta

Goccia

73 Wyndham St, Central, tel: 2167 8883 Aperitivo: 6pm-8pm - free buffet with purchase of one glass of wine Sample items: grissini with proscuitto, frittata, bruschetta

Gvsto

7/F Nexus Building, 41 Connaught Rd, Central, tel: 2147 3768 Aperitivo: 5.30pm-8pm - free buffet with purchase of one alcoholic drink Sample items: cured marinated swordfish, cold lamb with vinegar, beignets

The Lounge

JW Marriott, 88 Queensway, Admiralty, tel: 2841 3846 Aperitivo: Thursdays from 6.30pm-9.30pm - HK$168 plus 10 per cent for aperitivo buffet and a glass of standard alcoholic drink Sample items: selection of olive oils and bread, deep fried risotto balls, fried assorted seafood

Osteria

M/F, Holiday Inn Golden Mile, 50 Nathan Rd, Tsim Sha Tsui, tel: 2315 1010 Aperitivo: 5.30pm-8pm - HK$60 plus 10 per cent for aperitivo buffet, three 'warm bites' and one glass of wine. Sample items: in-house smoked salmon, savoury pastries, roast beef, selection of cold cuts and cheeses and 'warm bites' such as pasta, fried shrimp and chicken roulade

Spasso

4/F, Ocean Centre, Harbour City, Tsim Sha Tsui, tel: 2730 8027 Aperitivo: 6pm-8pm - free buffet with purchase of one glass of wine Sample items: grissini with proscuitto, frittata, bruschetta, crostini, pasta