Prep the base: Add onion, garlic, jalapeño, and bell pepper to the slow cooker.
Pour in the tomatoes, green chiles, black beans, and corn.
Season it well: Stir in chili powder, cumin, smoked paprika, oregano, salt, pepper, and tomato paste. Mix until the tomato paste dissolves into the veggies and spices.
Add liquids and chicken: Pour in the chicken broth. Nestle the chicken breasts (or thighs) into the mixture so they’re mostly submerged.
Let it simmer: Cook on Low for 6–7 hours or High for 3–4 hours, until the chicken is tender and easily shreds.
Shred the chicken: Remove the chicken to a cutting board and shred with two forks.
Return it to the slow cooker and stir to combine.
Finish with lime: Squeeze in the juice of half a lime, then taste and adjust seasoning with more salt, pepper, or lime as needed.
Serve and top: Ladle into bowls and add tortilla strips or crushed chips. Top with cilantro, avocado, cheese, and a spoonful of sour cream if you like. Add extra lime wedges on the side.