Seconding Dave at Lao-Thai -- I'm there every few months.
If you're looking for others, these are where I go...
Indian (General) -- Golden Cash and Carry, Kitchener
(Malayali) Palm Valley, Cambridge
Korean - KW Korean Market in the Krug St Plaza
Portuguese - Azores., Cambridge or Torreense, Kitchener
European (general) - ItaloFoods, Kitchener or Glogowska, Kitchener
Middle Eastern (general) - Ammar's, Kitchener