I really should visit India before I grow too old. There's so much veggie food to try. Recently met a childhood friend who, apparently, used to live there for decade. No he has a small Indian restaurant serving food that is nothing like the places I have been to in Europe and the UK. No garlic, no onions (I like both), etc. Love it
The no garlic and no onion are part of a much broader practice to avoid root vegetables. Anything that grows below the ground is not consumed. Jains (the people who follow Jainism) mostly follow this (I say “mostly” because even though they’re supposed to, many may not).
Orthodox Hindus may also follow similar practices. Hindu festivals and rituals also avoid onion and garlic.
There’s a lot more to say than can be contained in a comment. You can read about Jain food and Sattvic food to know more.
Also, like sibling comment says, jainism prescribes avoiding everything growing underground and you can ask for jain food if a place provides it. Some airlines make special affordances and have a jain meal option you can try.