Start by rinsing the chiles under cold water. Place them in a pot, cover with water, and bring to a boil. Reduce the heat and let them simmer for about 10 minutes until they are soft. Reserve 2 cups of this chili water for later use.
In a blender, combine the softened chiles, roma tomato, garlic cloves, half of the sliced onion, salt, and 1 cup of the reserved chili water. Blend until smooth. Adjust the consistency as needed by adding more chili water.
In a large skillet, heat a tablespoon of oil over medium heat. Add the blended sauce and simmer for about 5-7 minutes until it thickens slightly. Stir occasionally to prevent sticking.
If using corn tortillas, cut them into triangles. Heat the remaining oil in a frying pan over medium-high heat. Fry the tortilla pieces in batches until golden brown and crispy. Drain on paper towels and sprinkle with salt. If using prepared tortilla chips, skip this step.
Add the crispy tortilla chips to the skillet with the sauce. Gently toss to coat the chips evenly, allowing them to soak up some of the sauce while still retaining their crunch.
Transfer the chilaquiles to a serving dish. Top with crumbled Cotija or queso fresco, remaining sliced onion, and your choice of additional toppings such as cilantro, avocado slices, salsa, Mexican crema, or sour cream. Enjoy warm!
