Slice avocados and set aside.
Place cast iron skillet on high heat and when very hot, add one tortilla at a time and toast on both sides.
Heat cooking oil in skillet on high heat, and when oil becomes hot, lower the heat to medium-low and crack in as many eggs as will comfortably fit in your skillet.
Fry eggs slowly with cover on top of the skillet to create the perfect sunnyside up eggs. Repeat as necessary.
Once eggs are ready, you can build your Huevos Rancheros, layering the ingredients.
Place tortilla on the plate, then add black beans, add eggs and avocado, top with pico de gallo, and scatter some grated queso fresco.
Serve immediately.