Prep the base: Add the diced onion, garlic, canned tomatoes, tomatoes with green chiles, black beans, pinto beans, and corn to the slow cooker.
Pour in the chicken broth.
Season: Stir in taco seasoning, cumin, smoked paprika, and chili powder. Taste the broth and add a pinch of salt and pepper if needed. If using salsa or tomato paste, whisk them in now.
Add the chicken: Nestle the chicken breasts or thighs into the mixture.
They should be mostly submerged.
Cook low and slow: Cover and cook on Low for 6–7 hours or High for 3–4 hours, until the chicken is fully cooked and very tender.
Shred the chicken: Remove the chicken to a cutting board and shred with two forks. Return the shredded chicken to the slow cooker and stir.
Finish with freshness: Squeeze in the lime juice. Adjust seasoning with additional salt, pepper, or taco seasoning to taste.
Serve: Ladle into bowls and top with cheese, a dollop of sour cream, avocado slices, cilantro, jalapeños, and crushed tortilla chips.
Add extra lime wedges on the side.