Pour oil into a sauce pan to a depth of about 1½ to 2 inches.
Heat oil over medium heat.
Cut corn tortillas in half and then into thin strips using a sharp knife.
Once oil is hot fry tortilla strips until golden brown and crisp. Fry them in batches and drain them on a paper towel lined plate. Set aside while you prepare the soup.
Transfer 2 tablespoons of the oil into a large heavy bottomed pan.
Add diced onion and cook until onions are soft and translucent, about 5 minutes.
Add cumin, chili powder, oregano and bay leaf to the pot. Stir to "bloom" the spices and coat them with the onions and oil in the pan, about 2 minutes.
Add garlic and cook until fragrant, about 30 seconds.
Add chicken broth, tomato sauce, salt, sugar, and pepper to the pot. Stir to combine.
Increase heat and bring the mixture to a boil.
Once broth comes to a boil, add the chicken breasts.
Cover pot and simmer for 15 minutes or until chicken is cooked through.
Remove chicken from the pot and shred using two forks.
Add corn to the pot and simmer for 5 minutes or until corn is heated through.
Add the shredded chicken breasts to the pot and simmer for an additional 5 minutes.
Ladle soup into bowls.
Top each bowl with toppings of your choice; fried tortilla strips, cilantro, sliced radishes, diced red onion, cheddar cheese, sour cream and diced avocado to serve.