I second curtie's recommendation for Mumbai, in Palermo Hollywood. And I agree with smirkypants' note about porteños' evaluations of Indian food. Spicy stuff is just too foreign here!
At Mumbai, discuss the spice level with the waiter when you order. When I was there a week ago with some yanqui friends who love Indian food, I described our desired level of spiciness as very spicy for porteños, moderate for the rest of the world. The waiter laughed and brought dishes perfectly picante!
As for the food, it's quite good. A lamb dish was excellent. My only reservations are a rather short menu, lacking, predictably, vindaloos and similar mouth-burners, and prices that seem a little steep, though not outrageous.
Note that they don't serve rice with the main dishes, so order some when you order your food, or you'll wait a while for it to arrive.