I've said it before and I'll say it again: EatSafe Ottawa, the city's guide to inspections of the city's restaurants and food service businesses, is arguably the best restaurant directory online.
It includes every single food venue in the city. It's searchable by location, with full phone number and address info for each restaurant. And the city recently launched a site update with better search and navigation features, including the ability to search by food type - although so far it's not specific enough to distinguish between Thai and Ethiopian. Check it out here.
Related: Ottawa Food Guide