Service in restaurants in Mexico City is, to say the least, idiosyncratic. The other day I went to a place called Matisse in the Colonia Condesa. There were various salads on the menu, and I asked the waiter if they were appetizers or main courses. He looked at me with an inscrutable expression for a long minute, as if trying to figure out what I had really meant by asking that question. Finally, he said, "yes."