Suggestions needed: techniques to reach out to target clients(businesses) in India for validating a business idea

I am looking to reach out to my prospective clients (mostly restaurants) in India, more fore evaluating the idea itself and getting answers to some questions. The clients are not very technology savvy and I do not even expect them to have email ids.

I am in the United states and would like to have some advice on how should I get in touch with these prospective clients. Are there any local agencies that can help me out with this kind of data/response gathering?

This is part of the customer development and you should read Steve Blank's book. Also, there is nice step by step guide from Dharmesh Shah's blog http://onstartups.com/tabid/3339/bid/49760/Tips-For-Getting-Started-For-The-Non-Technical-Web-Entrepreneur.aspx In your case for step 4, you need to approach your prospective clients with some network or with the help of local folks in India.