The Tulum area is full of overpriced restaurants (some good, some not) so we were VERY happy to find Restaurare.
More than the food (which other reviewers have done a good job describing), the service was excellent, and the waiter/co-owner(?) spoke perfect English and gave us some good advice for our trip.
The also have a booth at the Saturday Tulum market at El Jardin de Frida.
FYI, they are closer to km 6 on the road, not km 4.