If you stay at Sri Raman Bihari Gaudiya Math, prasad is abundant. Otherwise, after a while you will probably want to venture out to get something to eat. While there are a lot of pure veggie places around, most of them use onions and garlic in some of their preparations. The Light Restaurant is one such place. You can steer clear of the onion and garlic problem by ordering items that aren't made with onion and garlic (chappatis, any paratha and most of the sabjis). It's not difficult to make a filling meal of a few parathas and a sabji, and the total cost will be less than Rs. 50. They are open from 10:30 AM until 11:00 PM. From the Namaskar Hotel, walk to the main bazaar, take a right, it's down on the left about ten minutes walk.
There is another similar sort of place nearer to the New Delhi Railway station, on Basant road in Paharganj. It's called the "Rishi Vaishnu Dhaba", and it's about a five minute walk down Basant road from the intersection of the Paharganj Main bazaar and Chelmsford Road opposite the railway station, past many many taxi, travel, and tour offices. If you are coming from the railway station, you cross Chelmsford Road and turn left down Basant road which parallels Chelmsford Road instead of going straight ahead into the main bazaar. There are some shops in the Paharganj area that sell tourist-oriented food and drinks.
One of the better places is The Khandelwal Store which is about a two minute walk from the Namaskar Hotel. Turn right when you reach the main bazaar. The Khandelwal Store is on your right a little before the Camran Lodge Hotel. They have many kinds of nuts, peanut butter and jam, snacks, drinks and juices. There is a fruit and vegetable market on a road just off the main bazaar where you can buy apples and bananas. It's just a little further up the road from the Khandelwal Store. If you need directions ask "where is the vegetable market" in hindi "sabzi mandi raha ha?". There is only one really good restaurant in New Delhi. The Vega Restaurant at the Hotel Alka (phone 334-4328) in the P-Block of Connaught Place. The auto rickshaw ride from Paharganj to the Hotel Alka costs about Rs30.
For some reason the auto rickshaw drivers have a hard time finding P-Block. It is located behind both A-Block and G-Block in the outermost ring of Connaught Place called Indira Chowk, between Bhagat Singh Marg and Baba Kharak Singh marg. Lunch or dinner will run you about Rs. 200 ($4) each. The clientele consists of tourists and upper-middle class Indians. Dressing western is not a bad idea here as the place is considered a splurge by Indian standards. Any brahmacari eating here will be the topic of everyone else's disapproving table conversation. The all-you-can-eat specials are very spicy. The paneer sizzler is great. It and the other entrees (but not the specials) are made to order. If you do not like chilli, tell them you don't want it spicy. There are some other pure-veg places mentioned in the travel guides found on the Travel Planning page. Keventner's isn't one of them, though by reading the Spiritual Guides write up you might think so. Just about everything there is made with eggs. A decent alternative can be found a few shops down on the side on A-Block near an HP Petrol filling station, "The English Dairy" is a pure-veg place that makes good parathas (remember to tell them to skip the onions). The paneer paratha is very nice (Rs20).