Add all of the ingredients to a medium-sized saucepan over medium-high heat. Once the mixture reaches a boil, reduce the heat to maintain a simmer.
Stir occasionally and allow to simmer for about 15 minutes, or until the onions and chiles are fork-tender.
Transfer the mixture to a blender or a food processor fitted with a blade attachment. Cover, remove the small blender cap or feed tube, cover the opening with a dishtowel, and blend until smooth.
ASSEMBLE THE ENCHILADAS:
For authentic enchilada rojas, add oil to a medium-sized fry pan over medium heat and bring to temperature. One at a time, fry the tortillas for about 5 seconds on each side. See notes below if you do not wish to fry your tortillas.
Dip the warmed tortilla in the sauce and transfer to a work surface. Add 2-3 tablespoons of shredded meat and roll or fold over to enclose.
Transfer to a plate, top with a generous spoonful of sauce, queso fresco, and any other desired toppings. Serve and enjoy!
Notes
HOW TO WARM TORTILLAS WITHOUT FRYING:
Working in batches of 4-6. Wrap the corn tortillas in a damp paper towel and place them on a microwave-safe plate. Microwave for about 30 to 45 seconds, or until very pliable and soft.