Here is the one I use. DH and I love it!
1 (14.5 oz) can Italian tomatoes with juices
3 T vegetable oil, plus additional for frying
1 whole skinless, boneless chicken breast, halved
1 med onion, chopped
3 garlic cloves, minced
2 t chili powder
2 t cumin
6 cups chicken stock or broth
1 T tomato paste
1 (4 oz) can chopped, mild green chiles, drained
1 T minced, seeded jalapeno peppers (about 2) or to taste
4 corn tortillas, cut into 1/2"-wide strips
2 T chopped cilantro (optional, but highly recommend)
Salt and Pepper
2 T grated Parmesan Cheese (optional, don't recommend)
1. In a food processor or blender, puree tomatoes in their juices (I usually puree green chiles and jalpenos with tomatoes, but you don't have to).
2. In large (4-quart or larger) saucepan, heat 2 T oil over medium heat. Add chicken and cook 3 min on each side. Transfer chicken to a plate. Add and heat remaining 1 T of oil. Add onion and cook, stirring frequently until golden (about 5 min). Add garlic, chili powder and cumin and cook, stirring frequently for 1 min. Add chicken stock/broth, pureed tomatoes, tomato paste, chiles and jalapenos (I usually pour in the tomatoes, then "rinse" my blender with some stock to get all of the puree).
3. Return chicken to saucepan, bring to boil. Reduce heat to lower, cover and simmer 20-30 minutes. Transfer chicken to cutting board, cut into bite-sized pieces and return to saucepan. Continue simmering, uncovered until ready to serve.
4. In a large skillet, heat 1/2-inch of vegetable oil over medium-high heat. Add tortilla strips in batches and cook, stirring frequently, until crisp (1 to 2 min). Transfer tortilla strips to paper towel to drain.
5. Skim the surface of the soup and season with salt and pepper to taste.
6. Divide tortillas among 4 soup bowls and ladle soup over tortillas. Sprinkle with chopped cilantro and parmesan cheese. Enjoy!
Hopefully this doesn't get moved. Sorry mods!
Edited to add:
DH and I like it spicy, so I will normally season the chicken with cayenne before cooking, and I will also add cayenne to the broth while simmering.