For authenticity, sub. lard for the olive oil. Garlic and onions have been imported to C.A. since the Spanish. Celery? I don't know. For Basil, Mexican oregano. Beef would be a festival food, so make vegetable stock, instead. Lime, avocado, corn, tomatos, jalapeno, all New World foods.
I wasn't sure about this one, but it is great! Wouldn't change a thing. Original poster's coments follow:
A wonderfully tasty, quick, low calorie, and filling soup--fit for Montezuma after a hard day at the sacrificial altar. Serve hot to 6 as complete lunch--or as a substantial first course.