In a medium bowl, combine the masa and salt. Mix with a fork. Gradually add the water, stirring until the dough starts to come together.
Switch to using your hands and knead until a smooth ball forms. The texture should feel like soft playdough. If the dough is too dry, add water 1 tablespoon at a time until the right consistency is reached.
Roll and Cut the Tostadas
Cut open a large storage (zip-top) bag along the sides so it opens flat—this will keep the dough from sticking.
Take a small ball of dough and place it between the plastic. Roll it out to about ⅛-inch thick.
Use a medium bowl or round cutter to cut into circles. Place each round between sheets of wax paper to keep them from drying out while you finish the rest.
Fry the Tostadas
Heat ½ to 1 inch of oil in a cast-iron skillet over medium-high heat to about 350°F.
Carefully place a tostada round into the hot oil and fry for 1½ to 3 minutes per side, or until golden brown and crisp. I did test cooking tostadas in an air-fryer, but didn't like the texture or color achieved.
Tip: If the oil is too hot, it will smoke. If it’s not hot enough, the tostadas will absorb too much oil and become greasy.
Drain and Season
Transfer the fried tostadas to a paper towel–lined plate to drain. Sprinkle lightly with salt on both sides while still warm. Let cool.
Serve
Top each tostada with refried beans, your favorite taco meat, and all your favorite toppings.