Remove the stems and seeds from the chile peppers. Place in a bowl, cover with hot water and soak until soft, about 20 minutes. Drain the chiles, transfer to a blender and process to make a smooth puree.
Heat the olive oil in a large pot over medium heat, then add the onion and garlic and cook until the onion is translucent. Add the tomatoes with their juice, 1/4 cup chile puree, the coriander seeds and cumin and cook about 5 minutes. Add the broth, bay leaves and thyme and bring to a boil, then reduce to a simmer and cook about
30 minutes. Strain the broth through a medium-mesh strainer into another pot, discarding the solids. Season with salt.
Place a small amount of chicken, queso fresco, avocado, cilantro, fried tortilla strips and sour cream in each bowl, then pour about 1 cup hot broth around the garnishes.