In a large, heavy-bottom saucepan with a lid, heat 2 tablespoons of olive oil over medium heat. Add the diced onion and sauté, stirring occasionally, until translucent (about 6 minutes). Add the remaining 2 tablespoons olive oil, and stir to combine. Add the flour blend, and stir frequently until the oil is thickened and the mixture starts to become fragrant, about 1 minute. Reduce the heat to low, and add the tomato puree, tomato paste, diced tomatoes, green chiles, stock, garlic powder, cumin, paprika, chili powder, oregano, salt and pepper, stir to combine well. Raise the heat to medium, and bring the mixture to a simmer.

Place the chicken breasts in the soup and press them down to submerge them completely in the liquid. Cover the saucepan with the lid, and cook until the chicken is opaque throughout (about 8 minutes, depending upon the thickness of the chicken breasts). Uncover the saucepan, transfer the cooked chicken to a plate or cutting board and shred the chicken with two forks while it’s still warm. If you are serving with ground beef instead of chicken, skip this step and proceed immediately to Step 3.

Add the black beans, corn and refried beans to the soup, and stir to combine, making sure the refried beans are incorporated fully. Ladle the soup into bowls, top with shredded chicken (or ground beef), sour cream, shredded cheese and crushed tortilla chips.