Of all the indian restaurants I've tried in Chiang Mai, Le Spice is my favourite. This place identifies as an indian, thai, and seafood restaurant. My suggestion: go indian.
The sets start at 99 baht and generally include two curries, a dahl, raita, papadum and rice. If you're with a group of people, it's always fun to order a number of dishes a la carte and share. Just think, the more people you're with, the more dishes you can try.
The menu is extensive. To aid the selection process, decide what kind of curry you're in the mood for [vindaloo, masala, saag, etc.] and then choose the meat/vegetable [chicken, mutton, beef, fish, paneer, etc].
To get there, drive down the night bazaar road and about midway you'll see the Kalare complex on your left. There is a Doi Chaang Coffee at the end of the complex. Turn immediately left down the soi and you'll see the brightly-lit Le Spice sign on the right.
notables | fish tikka. malai kofta [vegetable balls in a creamy curry]. vindaloo and/or masala [fish, chicken, mutton, you decide]. saag paneer [homemade indian cheese in spinach curry]. bengan bharta [eggplant curry]. any rice biriyani. lots of garlic naan. le spice naan [addition of dried fruit, coconut = funky].
sweet notables | kulfi [spiced rice ice cream]. kheer [indian rice pudding].
note | definitely vegetarian-friendly.