THOUGH the piano's gone walkin', the high notes left are better than ever. What used to be the Piano Bar, tucked away in Seibu's Food Hall, is now a nifty Mecca for the hungry - Kern's Fine Deli & Bistro. The continental food is as rustic and homey as the European decor. Creator Walter Kern (of Gastro Primo) and project manager Linus Knobel understand the time constraints of office warriors and shoppers. The more dining options and food choices, the better. At lunch, there's ''the giant pan'' - a take-away entree that changes daily. How about a wicked paella for $58? Best of all, the entree leaves in a specially-designed, leak-proof container that won't ruin a desk-top littered with contracts and checks in seven-digits. Take a chair in the 50-seat bistro and sip vin ordinaire ($22) or Taittinger Brut ($98) while musing the set three-course menu ($148). Or wing it with the a la carte version. At the takeout deli, create the evening's repast with a variety of homemade pastas (some filled) and sauces, antipasti, roasts (leg of lamb with thyme, veal, roast beef), ready-to-heat entrees (Hungarian goulash with spaetzle - boiled dumplings and osso buco - braised veal shanks), salad and desserts (apple strudel with cinnamon sauce, chocolate mousse with rum). Now there are no excuses not to entertain or spoil yourself after fighting the good fight in the boardroom or aisles. Insists Mr Knobel, ''we've got the best espresso in town''. Better yet, no service charge. Kern's Fine Deli & Bistro, Food Hall, Seibu. Hours: 10.30am-9.30pm daily. No reservations (yet). Tel: 973 0032. COOKING demos at the recently-held Green World Expo show that cooking smart happens to be health-conscious, ecologically and financially-sound. Appearances by cooking teachers/authors Yvonne Thompson, Lisa Fong, Doris Siu and Catherine Lai highlighted the weekend show. Ms Thompson advocates using organic produce, less oil, no MSG or artificial food colouring. Her tips help minimise waste, save energy and money. ''For sweet and sour pork, Chinese cooks traditionally use food colouring. A better choice is using colourful ingredients, such as red pepper or sweet corn. ''Most people never eat the garnishes. They think they're not edible, so the carrot flowers get tossed out with the parsley. That's a waste. Either encourage diners to eat the garnish or use foods they like. Skip parsley, a foreign taste to Chinese, and substitute shredded lettuce. ''For blanching vegetables, use water, not oil. And don't toss that water out. Re-use it for other vegetables or soup stock. ''Use water, not oil, to brown meat. It reduces the amount of fat in the diet and is cheaper. In deep-frying, however, water doesn't work because it doesn't impart crispness to the food. ''Cooks can easily reduce the amount of oil without sacrificing good results. Cook foods in smaller batches in a shallow saucepan with just enough oil to cover. Instead of four cups, use one.'' After frying meat, save the oil but be sure to filter the bits of fried meat by using filter paper. Store the filtered oil, covered, in the refrigerator. Until consumers demand organic produce in the supermarket, those prices will remain high. ''More awareness, education and demand will bring the prices down. Sometimes, the chain stores stock a small quantity of organic vegetables, but they don't label them properly. ''Since organic vegetables age faster than those grown with chemicals, consumers, seeing the limp-looking produce, ignore it. If it were labelled correctly, the store and consumer could benefit.'' FASTEN your bibs. Mooncake madness has started. At the Peninsula Hotel, chef Yip Wing-Wah of the Spring Moon restaurant is gearing up for peak production. By Mid-Autumn Festival (September 20), he and his staff of 32 will have produced 200,000 pieces. A box of eight sells for $100. Available now in the hotel's gift shop and the Peninsula store in the Landmark. And on Hong Kong Island, the Conrad's chef Dai, of the Golden Leaf restaurant, is cranking out two types: white lotus seed with egg yolk and egg yolk paste. His secret? Make them healthier by reducing the fat. His cakes (eight per box) retail for $98. ARE you the type who skips the ice cream dessert in order to save calories by ordering a cappuccino or caffe mocha? Think twice. A survey by nutritionists of Tufts University in Boston examined more than 50 varieties of coffee-based drinks from Starbucks and other coffee shop chains in America. What they found wasn't great news. A large caffe mocha contains about 400 calories and 30 grams of fat, which is 180 more calories and twice the fat of a serving of Haagen-Dazs ice cream, as reported in the July issue of the Tufts University Diet and Nutrition Newsletter. Any good news? Yep. The amount of fat in these drinks can be reduced by asking for skim milk or low-fat instead of whole milk. A large cappuccino has only 156 calories and 6 grams of fat when made with low-fat milk. LYN Hirschorn has secrets. Some are chocolate and cookware, others are pots of fresh herbs and porcelain table accessories. To avid shoppers like herself, the creator of Non-Stop Shoppers Unltd. shares tips and advice over Danish and coffee in a coach while the driver zooms to far-away places in search of bargains. Ms Hirschorn conducts all-day shopping tours from Central to warehouse grocery stores, the Gurkha Market, factories for candles, furniture and towels. Cost is $250, bring your own lunch, and reservations are required. Lyn's autumn schedule is available. Phone (523 3850) or Fax (868 1164) for a copy.