I also just want to say that I agree with prasantrin post above.
That's because you said it first! So really, I agreed with you!
You said it better though, and more clearly!
By the way, it's not just Jains that avoid onion and garlic so do not just assume that if they are not Jain, then you are ok. Certain Hindu sects also do it, and in addition some Buddhists. So best to ask and then you will be completely sure!