1 large dried pasilla (negro) chile, stemmed and seeded
One 15-ounce can diced tomatoes in juice (preferably fire-roasted)
2 tablespoons vegetable or olive oil
1 medium white onion, sliced 1/4-inch thick
3 garlic cloves, peeled
2 quarts chicken broth
1 large epazote sprig, if you have one
4 (about 1 1/4 pounds total) boneless, skinless chicken breast halves, cut into 1/2-inch cubes
1 large ripe avocado, pitted, flesh scooped from the skin and cut into 1/4-inch cubes
1 1/2 cups (6 ounces) shredded Mexican melting cheese (like Chihuahua, quesadilla or asadero) or Monterey Jack, brick or mild cheddar
A generous 4 cups (about 6 ounces) roughly broken tortilla chips
1/2 cup Mexican crema, sour cream or creme fraîche for garnish
1 large lime, cut into 6 wedges, for serving