I don't think you'll find a single source that provides authentic recipes for a wide variety of different ethnic foods. I think you'll need to find a good source for each type of food, unfortunately. I use a cookbook available in the US called Best Recipe which tends to be very good. They have an [International Version][1] which goes through many different types of food. It's a great book, but I'm not sure how authentic it is. So if you're looking for breadth and good recipes, it's a good one. But I don't think it would suffice to cook for a native. 


  [1]: http://www.amazon.com/International-Recipe-Cooks-Illustrated-Magazine/dp/1933615176