To make the tostadas: Preheat the oven to 450 degrees Fahrenheit. Spray each tortilla with cooking spray on both sides (I used organic olive oil spray) and place on a baking sheet in a single layer. Bake for about ten minutes, until golden and crispy.
To make the salsa: In a medium bowl, combine all of the prepared ingredients. Taste and adjust the seasoning if necessary (more lime juice, salt and pepper, etc.). Cover the salsa and let it rest for at least 30 minutes in order for the flavors to meld and the beans to soak up the surrounding flavors.