Adapted from Cook’s Ilustrated by Sarah
2 boneless, skinless chicken breasts (1 to 1/2 pounds)
8 cups low-sodium chicken broth
1 large onion (about 1 pound), trimmed, peeled, and quartered
4 cloves garlic, peeled
8 to 10 sprigs fresh cilantro plus 1 sprig fresh oregano
1 14.5-oz. can diced tomatoes, drained lightly
1/2 medium jalapeño pepper
1 chipotle chile in adobo, plus up to 1 tablespoon adobo sauce
1 tablespoon vegetable oil
Pinch of cumin
Salt and pepper, to taste
Broken tortilla chips (or strips)
Shredded cheese (cheddar or monterey jack) or crumbled cotija cheese
Bring chicken, broth, 2 onion quarters, 2 garlic cloves, epazote, and 1/2 teaspoon salt to boil over medium-high heat in large saucepan; reduce heat to low, cover, and simmer until chicken is just cooked through, about 20 minutes. Using tongs, transfer chicken to large plate. Pour broth through fine-mesh strainer; discard solids in strainer. When cool enough to handle, shred chicken into bite-sized pieces.
Puree tomatoes, 2 remaining onion quarters, 2 remaining garlic cloves, jalapeño, chipotle chile, cumin, and 1 teaspoon adobo sauce in food processor until smooth. Heat oil in Dutch oven over high heat until shimmering; add tomato/onion puree and 1/8 teaspoon salt and cook, stirring frequently, until mixture has darkened in color, about 10 minutes. Stir strained broth into tomato mixture, bring to boil, then reduce heat to low and simmer to blend flavors, about 15 minutes. Taste soup, adjust seasoning with salt, pepper, and, if desired, up to 2 teaspoons additional adobo sauce. Add shredded chicken and simmer until heated through, about 5 minutes. Ladle soup into bowls; garnish accordingly.