If you want good dimsum but don't have access to those in Markham or China Town, check out Kwan. Conveniently located steps from the Sr Clair subway station, Kwan serves dimsum till 4pm everyday. The selection is a bit limited (though there are good options for vegetarians) but the quality is good and it tastes clean (ie, not too oily). Gets a bit busy during lunchtime so get there when it opens or make a reservation.
I've also been here for dinner. Standard fare, with the standout being the Peking duck.