For street food- Kake di Hatti, lotan ke kulche, non veg in old Delhi, fatehpuri kulfi near Chandni Chowk, dolma aunty Momo's, Khandani Pakode near sarojini nagar For restaurant- u can visit cp, Khan market, hauz khas, saket
Chandani chowk and old old Delhi for both veggies n non veggies jamamasjid area for non veggies night lovers make visit to Khan market, Green park, CP , Lajpat nagar, Hauz khas village enjoy
Hi Neha, Delhi is a foodie's delight and there are so many options to choose from though i have attached an article for you giving the best suggestions by travelers on tripoto. Hope this helps!
Don't forget to eat Natural ice cream of Canaught place, south Indian food of sarwana Bhawan, Andhra thali of Andhra state house on Ashoka road. Jalebi with rabri in purani delhi, different types of samosa, moong dal pakoda near purani delhi metro station,kachaaudi sabhi of yamuna bazaar hanuman mandir, different types of pan in canaught place, Rajma chawal, chhole bhature in cp of shankar market.