Literally translated as "dry soup," sopa seca is really not a soup at all. It is, in fact, a dish usually based on rice, tortilla strips combined with tomatoes, onions and garlic and cooked in a broth. It's assumed that the name comes from the fact that, although the mixture begins "soupy," it is cooked until the liquid is entirely absorbedthereby becoming a "dry soup." The Mexicans usually serve sopa seca as a luncheon dish or as a separate course, much as Italians serve a pasta course.
From The Food Lover's Companion, Fourth edition by Sharon Tyler Herbst and Ron Herbst. Copyright © 2007, 2001, 1995, 1990 by Barron's Educational Series, Inc.