Heat ½ tablespoon olive oil in a 5.5-quart Dutch oven or large soup pot over medium heat before adding the ground turkey. Cook one side for 2-3 minutes until golden brown before breaking apart with a spatula and fully cooking.
Add the tomato paste to the cooked turkey, stir together, and cook until dark red, about a minute.
Add the taco seasoning, ranch seasoning, and a few tablespoons of broth. Stir together and deglaze the pot/scrape any sticky bits off the bottom. Add the remaining broth, beans, diced tomatoes, and frozen peppers and onions. Cover and bring to a boil, about 6-8 minutes. Reduce the heat to medium-low, stir the soup, cover, and simmer for another 10 minutes.
While the soup simmers, whisk the sour cream, cheese, and water together. Set aside. (Optional: Add 1-2 tablespoons of hot sauce to the cheese mixture.)
After the soup has simmered for about 10 minutes, reduce the heat to low and add the frozen corn to the soup. Ladle about 1 cup of the soup broth into the sour cream mixture and whisk together to temper before adding the cheese mixture to the soup. Stir everything together, cover, and simmer for another 5-10 minutes until the soup is smooth and creamy before serving.
Garnish with fresh cilantro and/or green onions, freshly sliced peppers, cotija cheese, lime wedges, and tortilla chips, if desired.