I concur with the recommendations for OP (with access to rental car & toll-pass, as our in-car GPS from Hertz kept steering us to use 407 Hwy ... to get around & avoid some of the worst traffic at most hours of the day, about as bad as LAX) - we just came back after spending a week & on this trip, stayed in the Thoronhill/Markham corridor - great choice of fine Chinese dining at all prices, many open early & stay late - excellent with the exchange rates.
http://www.theglobeandmail.com/life/...7179/?page=all
There are some good food stalls inside Pacific Mall, Markham - that catered mainly to the Chinese, but with the pictorial menus, it's easy for anyone else - just point & order (just don't go there early as many aren't ready till 11:30 & early in the week, the mall closed by 8 PM ... with heavy commuter traffic, you might still find the 30 to 45 minutes drive worth the trouble.) Let Google Nav be the guide as I found Waze NOT to be very helpful, run alongside Hertz's GPS in our rental vehicle).
DTF is spelled Ding (with the extra "g" at the end) and a quick check of their global/TW website definitely confirmed that it's NOT one of their worldwide location and just a knockoff. We came across & had XLB at this place called "Shanghai Dim Sum" on Hwy 7 in Richmond Hill - near another of the those Chinese malls nearby (about a block away) and they have special pricing for the 1st. tray of XLB - also, breakfast specials are served until 11 AM from memory.
Com Tam 168 is one of the better Vietnamese dining place around Markham & Scarborough area that we had a late lunch last week, part of the strip malls next to Pacific Mall - very reasonable prices & dishes, beyond the beef pho that some seasoned travelers are familiar with these days.
Congee Queen seems to be everywhere as a chain store - we ended up with Keung Kee Congee instead, also in the area. Not once did we eat in "old" Chinatown with its fading charcters - only noticed a handful of mom-n-pop dining places with limited appeals to us during our visit this time.
Opinions about food are always subjective & personal - YMMV. For dim sum, many places have discounts before 11 AM and after 1:30 or 2 PM - our orders were "steamed" to our selections, served hot and not expensive at all.