Lay chiles on their sides on racks of gas burners, 1 or 2 chiles per burner, then turn flames on moderately high. Alternatively, put chiles on rack of a broiler pan 2 inches from heat or on a hot grill.
Roast chiles, turning frequently, until skins are blistered and lightly charred all over, 4 to 6 minutes. Transfer chiles immediately to a large bowl, then cover with a plastic wrap. Steam for 10 minutes, then peel or rub off skin. Remove the stem, seeds and veins and dice. Set aside.
Heat the oil in large saucepan over medium heat. Add the onion and cook for 5 minutes or until softened. Add garlic, cumin, oregano, coriander and cayenne to pan; sauté 2 minutes more. Stir in tomatoes, chicken broth, green chiles, salt and pepper. Bring to a boil; reduce heat, and simmer 20 minutes. Add chicken, corn and beans; cook 10 minutes to heat through and cook the corn. Ladle into bowls and top with a little grated cheese and sour cream.
Nutrition information per serving:
Calories440Fat13 gSodium630 mg
Carbohydrates47 gSaturated fat5 gCalcium190 mg