Heat the oil in a large Dutch oven set over medium heat. Add the onion and saute 3-4 minutes, to soften. Stir in the garlic and cook another 1-2 minutes.
Add the turkey. Cook, breaking up with a spoon, 7-10 minutes, or until browned. Stir in the peppers and tomatoes and cook 3-4 minutes.
Stir in the broth, chile powder, cumin, beans, and corn. Simmer 15 minutes. Season to taste with salt.
Divide the soup among six bowls. Top with cheese, avocado, and any additional toppings that you like.