Dice all vegetables into similar-sized pieces (about ¼ inch). Mince garlic and have shredded cooked chicken ready.
Heat butter or oil in large stockpot over medium-high heat until shimmering. Add onions, celery, carrots, bell pepper, and garlic. Cook 5-6 minutes until softened and fragrant.
Stir in cumin, chili powder, and oregano. Toast for 30 seconds while stirring constantly. Add diced tomatoes, tomato paste, and chicken broth. Stir and bring to a rolling boil.
Reduce heat to medium-low and simmer uncovered for 10-15 minutes until vegetables are fork-tender.
Remove from heat. Using hand blender, carefully blend soup until smooth and creamy, keeping blender fully submerged. If using regular blender, cool 5 minutes, work in batches filling halfway, and hold lid with towel. This step is optional for chunkier texture.
Return pot to medium heat. Stir in kidney beans, black beans, corn, and pre-cooked shredded chicken. Heat through for 3-5 minutes until bubbling gently.
Taste and adjust seasoning with salt and pepper, adding ½ teaspoon at a time. Ladle into bowls and top with cheese, avocado, cilantro, lime, tortilla chips, and sour cream.
Notes
This recipe uses pre-cooked shredded chicken only. One rotisserie chicken yields approximately 3 cups shredded meat.
If soup thickens in the fridge, add a splash of chicken broth when reheating to reach desired consistency.
For Instant Pot: Sauté vegetables and spices, add tomatoes and broth, cook on high pressure 10 minutes with 10-minute natural release, blend if desired, then stir in chicken, beans, and corn.
For Slow Cooker: Sauté vegetables first, transfer to crockpot with remaining ingredients except chicken, beans, and corn. Cook on high 2 hours or low 4 hours, then add chicken, beans, and corn for final 15 minutes.
Keep blender fully submerged when blending hot soup to prevent splashing and burns.