Noida is dense with restaurants of every type — Indian regional cuisines, Chinese, fast food, mid-range chain restaurants and a growing number of independent cafes catering to the IT workforce. The Sector 18 area is the obvious hub, with hundreds of options inside the malls and along the surrounding streets.
Specific recommendations: Sagar Ratna in Sector 18 for proper South Indian dosa and idli; Big Chill at DLF Mall of India for its excellent baked pasta and chocolate cake; Sushi Junction in Sector 41 for relatively rare Japanese food; and the Andhra Bhavan-style canteens around Sector 26 for fiery, cheap Telugu thalis. Street food is generally fine in the Atta Market.