Warm oil in small skillet over medium heat. Stir in onion and celery and sauté briefly until soft but not brown. Set aside to cool.
In medium bowl, mix together the meat, cornmeal, and egg. Scrape onion-celery mixture into meat, followed by remaining ingredients, and stir them together lightly.
Form 3⁄4- to 1-inch meatballs, packing meat together lightly but firmly. If meat mixture sticks to your hands, rinse hands regularly with cold water. You should end up with about 48 small meatballs.
Warm 1 tablespoon oil in large heavy saucepan over medium-high heat. Brown meatballs in uncrowded batches, turning them frequently but gently. Drain with a slotted spoon and set aside on a platter.
Reduce the heat to medium and add 1 tablespoon oil. Stir in onion and sauté several minutes, until translucent, then add the flour and cook for another minute, stirring.
Stir in the tomatoes and juice, stock, water, optional azafrán, meatballs, and any juices. Bring just to a boil, then reduce the heat to medium low, cover, and cook for 15 to 20 minutes, until flavors blend and meatballs are cooked through. Salt to taste.
Ladle into broad, shallow soup bowls. If you wish, cut mint leaves into very thin ribbons and scatter over bowls. (Adapted from Tasting New Mexico, © 2012, by Cheryl Alters Jamison and Bill Jamison.)
ORDER IT HERE Papa Felipe’s, in Albuquerque, makes a nice Mex–meets–New Mex version called caldo de albóndigas. 9800 Menaul Blvd. NE; (505) 292-8877; papafelipes.com