My wife and I went to Chichén Itzá and, on our way back, stopped in Valladolid to see some sights, including the monastary. Taberna de los Frailes is right next to it (which we only realized after driving around town and ending up back there :).
Most of the seating is outdoors under a thatched roof. We came here for lunch - I had an allegedely authentic pork dish, which was the second best thing I had the entire time I was in Mexico (including several gourmet-style meals at the resort we went to later). My wife had a chicken dish that was also quite good. For the price, this was just amazing. Service was great, too. Definitely recommend