Shred cooked chicken into bite-sized pieces, setting aside.
Sauté diced onion in olive oil in a large saucepan over medium heat until translucent and fragrant, about 5 minutes.
Add cumin and chili powder to the onions, stirring for about 30 seconds until spices become aromatic.
Pour in the chicken broth and bring the mixture to a gentle simmer, allowing flavors to meld for 5 minutes.
Add the shredded chicken and cannellini beans to the broth, stirring to combine, then cook for another 10 minutes until heated through.
Stir in fresh lime juice to brighten the flavors, then remove from heat.
Ladle the hot chili into bowls, then swirl in a dollop of sour cream and garnish with chopped cilantro.
Serve immediately, enjoying the creamy, fragrant aroma and hearty texture of the soup.