AGUSTIN Gutierrez Canet cannot keep a secret. That's good news for home-bartenders or margarita buffs. To celebrate Mexican National Day today, the amiable consul general of Mexico surrendered his recipe for lethal margaritas. The diplomat was invited to become a teacher recently for members of the Lan Kwai Fong Association. He gave a lesson in margarita-making at California Restaurant to kick off the week-long celebration of Mexican food and drinks. His students included chefs and bartenders from the neighbouring establishments. ''The most important thing for a perfect margarita is balance,'' explained Senor Canet, beaming as he held court at the bar. ''You want a balance between sweet and sour. You've got to keep tasting the mixture. ''The flavour and taste depends on the fresh limes. Their sweetness changes, depending on the season.'' He faults most margaritas for being too sweet and overly iced. ''You don't want a frozen one. It dilutes the balance [of flavours] and it numbs the mouth. You can't taste much.'' He says gold or white tequila may be used. ''Use gold for a richer taste. But it is also more expensive.'' He prefers using Cointreau over Triple Sec for its softer, more floral taste. Fresh limes are an absolute must. Bottled concentrates are strictly forbidden. ''The fresh limes from Thailand are fine. So are those from the Philippines. If you don't have fresh limes, substitute fresh lemon. But the taste will be less flavourful.'' Salt on the rim is an option. His recipe is one part tequila, one part fresh lime juice, 1/2 Cointreau and crushed ice. He prefers to shake the drink by hand. Using the blender is okay, but control the quantity of ice. ''The trouble with using a blender is using too much ice. It melts faster in the blender and dilutes the taste. The drinks taste watery. '' He encourages home-bartenders to keep tasting. ''If you want it sweeter, add more Cointreau. If it's a bit too strong, add more ice. ''But be careful. An overly sweet drink ruins the appetite. ''Margaritas are served before a meal as an aperitif. They should stimulate the appetite and make you happy.'' Salud, Senor Canet. TWO chefs from Madras, India, are creating culinary magic at Spices. Those who enjoy Indian food without the overkill of rich sauces should investigate. The Taj Coromandel Hotel, Madras and Air India have imported the talent for the current promotion at Spices in the Repulse Bay Hotel. It runs until September 30. Recently, seven diners, including two Indians, hip-hopped around the menu, sharing cold and hot appetisers, tandoor and vegetarian entrees, a variety of breads and desserts. The consensus: no one suffered the discomfort that comes from overdoing it on rich gravies and generous amounts of ghee. Prices on the a la carte range around $35-$65 for appetisers; $62-$148, entrees. Luncheon buffet is $128 weekdays; $148 weekends.