Tarascan Soup
Blend in batches to a very smooth puree: 
1/2 c water
1 tomato 
1 white onion 
clove  garlic
1 ancho chile, cleaned and softened in warm water
1 corn tortilla
Sear this mixture in a hot pan with a little olive oil for a few minutes, then stir in: 
1 qt chicken stock
1/2 t dried oregano (use Mexican oregano if you can)
2 - 3 epazote leaves (optional)
Simmer over low heat until thoroughly heated.
Serve with toasted tortilla strips (lightly brush corn tortillas with olive oil, cut into strips, bake on a cookie sheet at 400 for 5 - 10 minutes until crisp), toasted ancho chile strips (slice dried ancho chiles into thin strips and saute them for a few minutes in olive oil), crumbled queso seco (or other dry cheese), and some kernels of fresh corn
Notes & Variations:
  1. This recipe was adapted from "The Art of Mexican Cooking", by Diana Kennedy, whose books on Mexican Cuisine form the Bible of Mexican cooking.
  2. The soup itself is a very light broth, but the ingredients you add when you serve it give it body and texture. You can stir in a few tablespoons of powdered pumpkin seed (toast pumpkin seeds and pulverize them in a blender or coffee grinder) to thicken the broth a little.
  3. Substitute shrimp stock, vegetable stock, or even water, for the chicken stock.
  4. Serve with wedges of lime.