Heat olive oil in a large stockpot over medium heat; add diced onion and sauté for 5 minutes until translucent.
Add minced garlic and cook for 1 minute until fragrant.
Stir in chicken broth, enchilada sauce, diced tomatoes, chili powder, cumin, salt, and pepper.
Place raw chicken breasts into the liquid and bring to a gentle boil.
Reduce heat to low, cover, and simmer for 15 to 20 minutes until the internal temperature of the chicken reaches 165°F (74°C).
Remove chicken from the pot, shred using two forks, and return the shredded meat to the soup.
Add black beans and corn to the pot and simmer for an additional 5 minutes.
Remove the pot from heat. To prevent curdling, whisk a ladle of warm broth into the Greek yogurt in a separate bowl before stirring the mixture into the soup until fully incorporated.