Place the chicken breasts into the crockpot. Pour in the diced tomatoes, chicken broth, add chopped onion, and minced garlic on top. Sprinkle cumin, chili powder, oregano, and a pinch of salt over everything.
Cover the crockpot and cook on low for 6-8 hours, or on high for about 4 hours, until the chicken is tender and easily shreds with a fork. The house will fill with a smoky, spicy aroma.
Once cooked, use two forks to shred the chicken directly in the crockpot, mixing it into the flavorful broth. This helps the chicken absorb all the smoky spices.
While the soup simmers, lightly toast the corn tortillas in a dry skillet until golden brown and fragrant, then cut them into strips or bite-sized pieces.
Add the toasted tortilla pieces and optional corn to the crockpot. Cover and cook on low for another 30 minutes, allowing the flavors to meld and the tortillas to soften.
Taste the broth and adjust seasoning with salt, or squeeze in fresh lime juice to brighten the smoky, spicy flavor profile.
Serve the soup hot in bowls, garnished with shredded cheese, chopped cilantro, and lime wedges for a fresh, tangy finish.
