My cousin did this same layover a couple of months ago, but brought food with her so she could spend time seeing the sites. She went to 2 museums, walked around a lot, and had her lunch in a park. She stopped in a department store which had a large food court and bought some fruit and chocolate at the end of the day (she does speak spanish, and had a copy of a kosher list that she found online). She took the metro to and from the airport. She spoke very highly of the experience, but frankly, the food was not the focus.