MAKE the tostone tostada shells by heating a shallow amount of oil (about ¼”) in a medium saucepan. Cook the plantain slices until golden all over, rotating as necessary to get all sides golden. Try to avoid them getting brown. Depending on the size of your pan, you may need to do this in batches.
SMASH the cooked plantains while still hot with a kitchen mallet or the flat bottom of a mug until flat and thin. Cook again in the shallow oil over medium-low heat, about 3 minutes on each side until crispy. You will need to do this 2-3 at a time, depending on the size of your pan. Sprinkle tostone with salt immediately after cooking.
WARM the refried beans and black beans each on the stove or in the microwave.
BUILD your tostada by laying on top of the tostone with refried beans, black beans, guacamole, shredded lettuce, pico de gallo and other toppings of choice, such as a drizzle of ranch, chopped cilantro, and jalapenos.
SERVE and enjoy!