Place chicken in slow cooker with salsa, lime juice, garlic, and black beans. Cook on low for 7-8 hours or high for 5-6 hours. Shred chicken. Season with mexican seasoning.
Assemble salads by topping romaine with shredded chicken, black beans, corn, white cheddar, red onion, green onion, serrano pepper, and cilantro. Serve with salsa or guac.
Recipe by Rachel Schultz at https://rachelschultz.com/2014/03/12/crock-pot-chicken-taco-salad/