The better option to book a restaurant in India will be provided by some information portal I guess, since It will let you know the available restaurants throughout India. If you are seeking to celebrate a holiday then I would suggest you to visit Kota as there are abundant restaurants in Kota
Hi! India is a great place. I'd love to visit there.
So what is the best way to book a restaurant in India without roaming?
I'd say going into a restaurant and asking to book a table! One of India's official languages is English, so you should not have a problem speaking to restaurant staff. There should be someone who will be fluent enough to speak to you. If not, you could try speaking some Hindi!
Or, you could find an old-fashioned pay phone! According to www.spiritualjourneys.net/TelephonesIndia.htm, there are payphones all over the country, even in remote villages. You could use your phone when you have a wifi connection in a cafe or hotel for example to find the restaurant's phone number, and then use a pay phone to make the reservation. According to the above website, pay phones in India are manned, which means there will be an individual to help you. You just pay them, rather than putting coins in a slot.
I hope I've helped. Here's a video about the top 5 restaurants in India!