In a large skillet, heat about a centimeter of vegetable oil over medium-high heat. Carefully place one tortilla at a time into the hot oil.
Fry for 1-2 minutes per side, or until golden brown and crispy. Remove with tongs and place on a paper towel-lined plate to drain. Season with a pinch of salt. Repeat with all tortillas. Alternatively, you can bake them at 180°C for 10-15 minutes until crispy.
While the tortillas are cooling, heat the refried beans in a small pot or in the microwave. Prepare all your toppings: shred the chicken, chop the lettuce and tomatoes, and crumble the cheese.
To assemble, spread a thin, even layer of warm refried beans over a crispy tostada shell.
Top the beans with a generous portion of shredded chicken, followed by lettuce or cabbage, tomatoes, and crumbled cheese. Finish with a drizzle of sour cream and a spoonful of salsa. Serve immediately to enjoy the crunch!