Line a toaster-oven pan with foil and arrange tortillas on it. Top the tortillas with beans and cheese. Toast until the cheese is melted and the tortillas are starting to brown along the edges, 7 to 8 minutes.
Meanwhile, place greens in an individual salad bowl. Drizzle lime juice and oil over the greens.
Remove the tostadas from the toaster oven and top with avocado and pico de gallo (or salsa). Serve hot with the dressed greens.
Percentages are based on a diet of 2000 calories a day.