Navdanya is one of the foremost Indian NGOs working for ecological, agricultural, and women's issues. The Navdanya Cafe at Dilli Haat leverages their relationships with organic farmers across the country to provide meals and snacks made from organic ingredients. The menu features organic versions of popular street food as well as several more creative inventions (my favorite of which is the amaranth cutlet). Several dishes include dairy (paneer, etc.), but there are plenty of vegan options.
The cafe also serves as a shop, selling a great variety of organic dry goods such as grains, pulses, spices, herbs, etc. at reasonable prices.
The setting is a quiet back corner of Dilli Haat, a government-operated market featuring booths selling crafts and vittles from every state across India. Dilli Haat is conveniently located immediately south of the INA metro, on the west side of Aurobindo Marg (across the street from INA market). There's a Rs 20 admission fee to enter Dilli Haat (buy tickets from the window near the front gate).
It's a very casual affair, so don't expect table service or anything fancy, but they're nice people working for a great organization and serving good food at fair prices - especially since it's one of the handful of organic restaurants in Delhi - so it's worth a visit.