Adelaida Cuellar, founder of the tamale stand that grew into the El Chico restaurant chain, was born on May 30, 1871, in Nuevo León, Mexico. In 1892 she and Macario Cuellar crossed into Texas and were married in Laredo. At the time they spoke no English. They worked on ranches in small Texas towns before settling as sharecroppers in Kaufman. In 1926, with twelve children to support, Mrs. Cuellar decided to supplement the family income by selling homemade tamales at the Kaufman County Fair. The tamale stand was a success, and the venture was repeated the following year. Soon after, sons Frank and Amos opened a Mexican cafe in Kaufman with Mama Cuellar, as she was called, doing the cooking. The cafe closed after two years, as the Great Depression tightened its grip on the community. Eventually, using her recipes, several of the sons opened Mexican restaurants in the East Texas towns of Terrell, Wills Point, Malakoff, and Tyler, as well as in Oklahoma City, Oklahoma, and Shreveport, Louisiana. All of these ventures closed by the end of the 1930s.
In 1940 Mrs. Cuellar's sons Macario and Gilbert moved to Dallas and opened a restaurant, El Charro, in the Oak Lawn neighborhood. The menu featured Mama's tastiest recipes, and eventually most of the family moved to Dallas to help with the popular business. Within three years the restaurant was profitable, and the family began to expand its interests into other parts of Dallas and Fort Worth, Waco, and Houston. By this time, the restaurants had become known as El Chico and the Cuellar sons as "Mama's boys." The family expanded and diversified the business rapidly, entering the frozen food business in 1955 and opening restaurants throughout the Southwest. By the time Mama Cuellar died, the El Chico Corporation was involved in twenty separate business enterprises, from restaurant franchising to canning. Adelaida Cuellar was a member of Holy Trinity Catholic Church in Dallas. She died on April 13, 1969, in Dallas and was buried at Calvary Hill Cemetery.