Indian is great for Vegan options.
Onion Bhajis and Samosas are vegan, along with usually any batter as it's made with chickpea flour... vegetable pakoras will be vegan.
For sides, I don't think naan breads generally are but you are safe with all other breads so chapatis, rotis, puri etc knock yourself out!
Some Indians use butter in their Pilau rice so if you're unsure it's always better to go with plain.
As for mains there are loads of options. A lot of the more authentic sauces are naturally vegan - your Bhunas, Madras etc aren't made with milk and are generally tomato based. So you can order a vegetable curry in a tomato based sauce, however, most places are fine if you just ask for it to be made with oil instead.
Additionally, Dhals are great, however again ask for no dairy to be used.
For fool proofs I usually say either go with a Chana Dhal or Bombay Potatoes.