In a medium saucepan, heat the oil. Cook until the onions are tender, 2 to 3 minutes. Cook for a few minutes more after adding the tomatoes, green chilies, cumin, salt, and black pepper to taste. Keep heated and set aside.
In a separate medium nonstick skillet or griddle, generously spray the tortillas on both sides with oil and fry over medium-high heat until crispy and pockets or air bubbles develop within, about 1 to 2 minutes on each side. Place aside.
Reduce the heat to medium-low and gently coat the pan with additional oil before adding the eggs, salt, and pepper. Cook until the whites are set for sunny-side up, or until done to your taste.
To serve, top each dish with two tortillas, half of the tomatoes, two eggs, lettuce, cheese, and cilantro.