Modest, highly functional self-service vegetarian place. All the food is Indian vegetarian, and served charmingly in Indian stainless-steel wares. The menu is limited to a bit of salad, a few sauces, two kinds of rice, five mains, one "European" dish, and some additional items like samosas. You pay for everything by weight except for the individual items like samosas, which are charged for by the unit. The salad greens didn't seem exceptionally fresh, but in general the food was not overly heavy or fatty, and had lighter options mixed in with heavier ones.
There's tap-water at every table, which is a nice touch and unusual for Europe. There's also free and low-hassle Wifi. That makes this an especially attractive resting spot for travelers. At the Na Poříčí location, though, which is just out of the main tourist areas, just about everyone seemed to be a local, many office-workers popping in for a quick meal.
Note that you can reach this location from both Na Poříčí and Na Florenci. It's actually in a courtyard in the middle of the block between those streets (with not much street signage). The outdoor seating is shaded, and of course you can sit indoors too. It's open long hours and has a very pleasant interior.
Cons: limited menu, not much day-to-day variety