Heat 1/8 to 1/4-inch oil over medium-high heat. Fry tortillas 30 seconds on each side to light golden, 1 tortilla at a time. Drain tortillas on brown paper sack. Season with a little coarse salt while hot.
Heat beans in microwave or small pan over moderate heat. Spread hot beans on tortillas and top with a handful of shredded smoked Cheddar or Jack cheese. Top cheese with shredded lettuce, diced tomato bits, and chopped onion. Garnish tostadas with chopped fresh cilantro or parsley and serve.