Tortilla soup

Olive oil, extra virgin	2 tablespoons
Onion, white, thinly sliced	1 large
Garlic, thinly sliced	5 cloves
Salt, kosher
Tomatoes, plum, halved	1 ½ pounds
Chipotle chiles in adobo sauce, seeded, coarsely chopped	4
Chicken stock	8 cups
Canola oil
Tortillas, corn, halved, thinly sliced	6
Butter, unsalted, diced	8 tablespoons
Chicken, rotisserie, shredded	4 cups
Queso fresco, crumbled	garnish
Cilantro leaves	garnish
Chile, dried	garnish

1. In a saucepan, heat the olive oil until shimmering. 
2. Add the onion, garlic, and a generous pinch of salt. 
3. Cook over moderate heat, stirring, until softened and starting to brown, about 10 minutes. 
4. Stir in the tomatoes, chipotle chiles, and stock. 
5. Bring to a boil, reduce to moderately low heat, simmer and stir occasionally until the tomatoes are very soft, about 30 minutes. 
6. Meanwhile, in a skillet, heat ¼ inch of canola oil. 
7. Add half of the tortilla strips, and fry over moderate heat, stirring, until crisp, about 2 to 3 minutes. 
8. Using a slotted spoon, transfer the strips to paper towels. 
9. Season with salt. 
10. Repeat with remaining strips. 
11. Carefully ladle half of the soup into a blender, and add half of the butter. 
12. Puree until smooth, and pour into a large saucepan. 
13. Repeat with remaining soup and butter. 
14. Stir in the shredded chicken, and gently reheat the soup. 
15. Season with salt, if necessary. 
16. Serve in bowls, garnished with queso fresco, cilantro, chile, and tortilla strips. 

Recipe from Food & Wine May 2013.