Spray each side of tortillas with cooking spray and place on a baking rack. Bake in oven at 375 degrees for 7 to 10 minutes until golden and crunchy, turning half way through. Or use store-bought tostada flats warmed in the oven.
Mix just enough sour cream into warmed refried black beans to make them smooth, creamy, and easy to spread. Spread bean mixture on tortillas and set on plate.
Fry, poach or microwave four eggs in your preferred method sunny side up or over easy, individually. Place one cooked egg on top of each tortilla.
Top tortilla, bean, egg creation with salsa or tomato sauce, grated cheese, and a drizzle of Crema. Enjoy!