Mix the masa harina with the cold water and blend until smooth. In a large saucepan, stir together the broth, cumin, tomatoes, masa harina mixture, salt and pepper, and hominy. Bring to a boil, reduce the heat and simmer for 5 minutes, stirring occasionally. Toss together the cilantro and lettuce in a bowl. Add the avocado to the soup just before serving. Serve the soup, and pass around the lettuce and cilantro at the table, letting everyone put some on top of their soup. NOTE: "It may seems weird putting your salad in the middle of your soup. It isnt. The salad looks great and stays crunchy in the middle of the soup, adding a sparkling contrast in texture. Posole is the Spanish name for hominy soup." Recipe by: The Supper Book - Marion Cunningham Posted to MC-Recipe Digest V1 #957 by KSBAUM on Dec 15, 1997