Fry corn tortillas in 1-inch of hot oil until crispy. Set aside on paper towels to drain excess oil. Warm the black beans in a saucepan over medium heat. Add tomatoes, onion, cilantro and salt and pepper to saucepan. Reduce sauce over medium heat until flavors meld and ingredients come together. Fry eggs over-easy or over-hard in fry pan.
To assemble: Plate corn tortillas. Top with black beans. Place eggs over black beans. Add rancheros sauce on top of eggs. Garnish top with avocado, sprig of cilantro and a side of sour cream.