Hi Jamie,
I would say that the large majority of folk in India are vegetarian, and you will have no trouble at all finding vegetarian meals.
There will be no trouble in getting a vegetarian meal.
But a majority of Indians are not vegetarians. A majority of upper caste Indians are vegetarians. But this is currently a politically fraught subject in India. Most tourists would not come by the invisible lowest caste Indians, so they can be excused for forming a wrong impression.
Most of the UK Indian restaurants are run by Bangladeshi people, so the impression we get is influenced by their cuisine, a Northern or Mogul, less vegetarian style.
Irrespective of who runs the Indian restaurants, the normal north Indian cuisine served in them is northwest Indian. Very few Bangladeshi eat at home what they serve in those restaurants. Trust me, I am of the same ethnic group. A Bengali.
We generally eat tremendous variety of Fish, Rice, Daal, Eggs (Chicken and Duck) and a mind boggling variety of Vegetarian dishes too. Jokingly we say that we can make a Saag preparation out of virtually any pile of fresh leaves collected in the field.
On the meat side Goat, Mutton and Chicken are popular. Among the Muslims Water Buffalo and even some true Beef goes, but they are generally more expensive and there fore not a staple food like Fish.
The restaurant cuisine in the west has more to do with the British love affair with the so called "Martial Races" of northwest India than with what Indian in general eat. That tradition of Restaurant fare lives on after almost a century. It is actually quite hard to get real Bengali Cuisine in restaurants. Many Bangladeshi restaurants will serve it off menu in the back room if you ask them in Bengali. Oddly enough, until about 30 years back it was hard to get good Bengali cuisine even in upscale restaurants in Calcutta. Now the Bengali Cuisine restaurants are the rage in Kolkata.
South Indian food is quite different, and tends to be a lighter type of cooking, less oil, less breads, dare I say more vegetarian. Each state has its own style of staple food favourites.
Indeed, as you might have figured out from my short rant on Bengalis and Bangladeshis above.
As to curry itself, it is not exactly a concept in India. Indian folk seem to enjoy a level of "spice" in most of their foods, there are many different spices and flavours added to different dishes.
Curries in the present form were actually popularized by Railway Refreshment Rooms in India. There is even a thing called "Railway Curry" that is served even today. The popular non-veg menu items in the Delhi Jn. Non Vegetarian Refreshment Room in the '60s were "Mutton Curry Rice", "Rice Curry" (that was Goat), "Chicken Curry Rice" and "Egg Curry Rice". There was and is a separate Vegetarian Refreshment Room.
But indeed if you go to a north Indian home, they would generally not be eating curries too often. We seldom eat curries at home, though the spices used in curries are used in other preparations that taste nothing like the classic curry.
Some foods, for example "idlies" are plain rice cakes, and one adds some mild flavours to them with a choice of "sambar", a very mild sauce, or a coconut flavour sauce.
You need to make sure that you ask for a mild sauce. There are certain parts, coastal Andhra Pradesh comes to mind, where normally they will serve a sauce that will clear your bowels for the next two days.
There are many hotels that cater for the better off Indian guests in most cities, and one can find non spiced items on their menues. Those in tourist spots are aware that internalional visitors may prefer mild foods. One can ask for no spices in omlette, etc. There are many other styles of cooking to be found in India, such as Chinese influences, pizza, even KFC in larger cities.
Indian Railways IRCTC food service will generally have at least one item identified as "Western" on their fare which will be something like a roast Chicken with Potatoes and such, pretty bland stuff, for those that cannot handle spices.
Another dish that is quite popular for a quick meal these days is the Biriyani. It is a Rice preparation with some spices and a protein additive of your choice (if non-veg). It is a meal in itself, and you don't have to deal with separate sauces and what not. Nothing to spill. Usually may come with a bit of Achaar - a spicy preserve of Mango or other veggies. Just avoid the hot stuff.
Incidentally beware that a very popular additive to Omelettes is little pieces of green chilly, which can be hit or miss as far as the level of heat goes. They are completely unpredictable, but it is also easy to sort them out and avoid them even if they are in the Omelette. They usually do not propagate their heat to the rest of the Omelette. They do add a nice subtle flavor if you like such.
I am sure Jishnu will have some input, being a more up market type of guy than myself.
Hope I obliged adequately
Actually, though I would know more about down market street food and local food than up market anything since I seldom go to any restaurants in India. Those are for the tourists and foreigners and for extremely special celebrations where you want to spend a lot of money.
