In a large saucepan, heat the olive oil. Cook the onion over medium heat until softened, 5 to 7 minutes.
Add the garlic, chili powder, cumin, crushed red pepper, paprika, oregano, sugar, salt and pepper and cook, stirring for 1 minute.
Stir in the tomatoes and remove from heat. Blend the mixture in a food processor or blender until smooth.
Return the tomato mixture to the saucepan and bring to a simmer.
Add the chicken breast and cook, covered for 10 minutes.
Preheat oven to 350 degrees.
Flip the chicken breast, cover and cook for 10 minutes, until the chicken is no longer pink and cooked through.
Transfer the chicken to a cutting board and use two forks to shred it.
In a large mixing bowl, combine the chicken with the corn, ½ cup of the tomato mixture, and ½ cup of the cheese.
Wrap the tortillas in a damp paper towel and warm them in a microwave oven until soft and pliable, about 15 to 20 seconds.
Spread a thin layer of sauce on the bottom of a 9" x 5" glass loaf pan. Arrange the tortillas on a work surface. Divide the chicken mixture between the two tortillas.
Roll up the tortillas and arrange in the loaf pan. Top the enchiladas evenly with the remaining sauce.
Sprinkle the tops of the enchiladas with the remaining ½ cup of cheese.
Bake for 15 to 20 minutes, until the enchiladas are hot and the cheese is melted.
Serve warm with sour cream.
Notes
Be sure to add a thin layer of sauce on the bottom of the loaf pan. Doing this will keep the tortillas from sticking to the baking dish.
Warm the corn tortillas for a few seconds in the microwave. Corn tortillas are not as soft as flour tortillas and warming them up will make them softer and easier to roll.
Adjust the heat of the dish to your taste. These enchiladas are rather mild. If you prefer a spicier dish, consider adding some red chilies or jalapenos to the filling.