Combine all the ingredients in a food processor or blender and pulse a few times, until mixture is mostly combined, but still slightly chunky. Set aside. (can be made up to a week ahead of time, store in an air-tight container in the fridge)Combine all the ingredients in a food processor or blender and blend until smooth. These can be made up to 4 days ahead of time. (store in an air-tight container in the fridge)Preheat oven to 400 degrees F. Line a large baking sheet with tinfoil and lightly spray with cooking spray. Place the tostada shells in an even layer on the baking sheet.Spread about 1 to 2 tablespoons of the black bean mixture over the top of each tostada, then sprinkle with a couple tablespoons of shredded cheese. Bake for 3 to 5 minutes, or until cheese is melted.Meanwhile cook your eggs to your preference. The eggs pictured are "sunny side up." Lightly coat a skillet with non-stick spray and heat over medium-high heat. Crack the egg into the skillet, season with salt and pepper, and cook for 2 to 3 minutes, until whites have set and yolk is still runny.Place cooked eggs on top of the hot tostadas, top with the avocado salsa verde, sliced tomatoes, fresh cilantro and a little cotija cheese. Enjoy!