My wife and I spent an interesting couple of hours st Mingcha yesterday and found it most interesting. Mingcha is a purveyor of fine tea that they source from all over China and the "tea house" located on the 12th floor in an Industrial building is where you get to sample their wares.
Get there by taking the MTR to Tai Koo and exit the station at A1. You will see a gas station directly across the road and the entrance to the building to the right. The Entrance is a long hallway. Continue nearly to the end then turn right into what looks like a carpark. The elevator is to the right on the opposite side to where you entered. Take lift to the 12th floor and ring the bell at the right of the door.
Our guide yesterday was Fiona who did a very good job explaining the teas with no pressure to purchase anything, even though I recommend you do, as the tea is fabulous.