I guessed you're in this business. I know they use ceylon tea leaves. Some tea do have a richer tea taste. Many years ago I met an owner who just bought a fast food shop. As he knew nothing about the trade he had to hire the barman who worked in the shop. One year later, the shop closed down. Of course it's different in Malaysia. I have an idea, why don't you come to HK, have your meals at the same restaurants everyday, make friends with them and ask them if they'll show you how, or try to observe the brands of tea they are using, they usually put their stocks under the seats or high up. But as I've said, 90% is from Tsit Wing Coffee. So better contact them for the blend of tea, I'm sure they'll show you how if you order from them, since they provide both tea leaves and machines.