In 3 1/2- or 4-quart slow cooker, place chicken thighs. Sprinkle with taco seasoning mix. Top with chiles. In medium bowl, mix tomato sauce, cumin and coriander seed. Pour over top. Top with beans.
Cover; cook on Low heat setting 7 to 8 hours.
Remove chicken from slow cooker; place on cutting board. Mash beans in slow cooker. Shred chicken with 2 forks; return to slow cooker, and mix well.
To serve, spoon about 3 tablespoons chicken mixture into each taco shell. Top each with 1 tablespoon cheese, 1 tablespoon lettuce, 2 teaspoons sour cream and 2 teaspoons salsa.