Hi there,
For many years i have been looking for a great Thai restaurant in Paris. I did almost all of them. Bu this one you have to try, it's located in a little street in the 19th arrondissement, owned by a old married couple (they do everything from cooking to service, they have no employees).
The restaurant is called Thu Thu, You HAVE to book it before you go as they are not many tables, here's the address: 51 Rue Hermel. I don't have their phone number anymore. Just have a look in the yellow pages.
Let me know what your feedback