In a nonstick skillet over medium-high heat, add the bacon and cook, turning halfway through, until crisp, 10 to 12 minutes. Remove to a paper towel-lined plate.
Meanwhile, in a saucepan over medium heat, add the vegetable oil, black beans, a pinch of salt and pepper and some hot sauce. Heat until warmed through, mashing the beans with a fork.
On a baking sheet, layer: 1 tostada shell, 2 tablespoons beans, 1 tablespoon cheese, 1 tostada shell, 2 tablespoons beans, 1 tablespoon cheese, 1 tostada shell, 2 tablespoons beans and 1 tablespoon cheese. Bake until the cheese is melted completely and the edges of the tostadas are beginning to turn golden, about 3 minutes.
Meanwhile, heat 1/4 inch of vegetable oil in a nonstick skillet over medium heat. Add the egg and cook until the white is set but the yolk is still runny, 5 to 7 minutes.
To serve, transfer the tostada to a plate, top with the fried egg, diced avocado, salsa, sour cream, a sprinkle of the remaining cheese and the cilantro. Place the bacon on the side and enjoy.