Upupi Palace is probably my favorite Indian restaurant in Chicago. There are tons of menu options that are vegan or can easily be made vegan. This place is especially worth checking out if you have never been to a South Indian restaurant - the menu is quite different from most Indian restaurants that you find in the US. You won't find channa masala or naan on the menu, but you will find a large selection of dosai (crepes filled with various vegetables) and curry dishes. My favorite menu item is the masala dosai, a huge crispy "crepe" made from lentils, filled with potatoes and onions, and served with various sauces.
Unfortunately, the restaurant does not label vegan dishes on the menu, but I have always found the waiters at Udupi Palace to be very helpful in this regard. On thing to keep in mind is that parking on Devon Street can be nearly impossible at times, so leave yourself plenty of time to look for a parking space (or take the CTA).