6 tablespoons cooking oil
8+ 6-inch corn or flour tortillas, halved and cut crosswise into 1/4-inch strips
2 onions, chopped
6 large cloves garlic, smashed
1 tablespoon paprika
5+ tablespoons ground cumin
4 tablespoons chili powder
2 teaspoons cayenne pepper
1 1/2 quarts canned low-sodium chicken broth or homemade stock
3 cups canned crushed tomatoes in thick puree (one 28-ounce can)
2 bay leaves
2 1/2 teaspoons salt
1/4 cup lightly-packed cilantro leaves plus 3 tablespoons chopped cilantro
1 3/4 pounds boneless, skinless chicken breasts, cut into 3/4-inch pieces, or soya-meat equivalent
1 avocado, cut into 1/2-inch dice (optional)
1/4 pound cheddar, grated
2 limes worth of juice
Lime wedges, for serving

In a frying pan, heat the oil over moderately high heat. Add half the tortilla strips and cook, stirring, until pale golden, about 1 minute. Remove with a slotted spoon and drain on paper towels. Repeat with the remaining tortilla strips.

Reduce the heat to moderately low. Add the onion, garlic, cilantro and spices; cook, stirring, for 5 minutes.

In a large pot, prepare broth, add one third of the tortilla strips and the onion mixture to it (saving the frying pan for the chicken later) (only one-third of the tortilla strips), along with tomatoes, bay leaves, salt, cilantro leaves. Bring to a simmer. Cook, uncovered, for 30 minutes; remove the bay leaves.
While the soup is simmering, sautee the chicken until white and almost done (I usually add salt, pepper, and lime juice to add flavor).

In a blender, puree the soup in batches; pour it back into the pot. Add the chicken, bring the soup back to a simmer, and cook until the chicken is done, about 4 to 5 minutes. Stir in some of the cheese, the lime juice and the avocado.
To serve, put half of the remaining tortilla strips on the bottom of the bowls and pour in the soup. Top with the remaining strips, cheezse, sour cream, cilantro, etc. and serve with the lime wedges.