Warm the ranchero sauce and the beans in separate saucepans (or use microwave).
Heat a small amount of oil in a fry pan, and crisp the tortillas - this will only take a few seconds. A flour tortilla will puff up slightly. Drain on paper towels.
Add a bit more oil to the pan, and fry the eggs, basting with oil to set the tops.
Place two tortillas on each plate, spread a spoonful of beans over each tortilla, and top each with an egg.
Spoon 1/4 to 1/2 cup ranchero sauce over the eggs, and top with crumbled queso fresco.