Tortilla Soup Recipe. Corn tortillas were a staple of the Mexican diet long before the Spaniards arrived in the 16th century. Historically, tortillas were made fresh daily without preservatives, so they quickly became tough. After Spanish cooks introduced soups to Mexico, day-old tortillas found their way into nourishing broths. Adding them to a chili-spiked soup was a thrifty way to revive an ingredient.
Recipe courtesy of Williams-Sonoma.