Toss diced potatoes in a large skillet with a couple tablespoons of olive oil. Cook until soft.
As potatoes cook, warm pinto beans in a small saucepan over low heat.
Once potatoes are soft, season with chili powder, ground cumin, paprika, garlic powder, onion powder, salt, and pepper. Stir around so everything is coated. Continue to cook, as they crisp up slightly.
To assemble, make a bed of shredded lettuce on a tostada. Scoop a serving of pinto beans and potatoes and place on top. Top with desired toppings and enjoy.