Set large non-stick skillet over medium heat; grease well with non-stick cooking spray. Crack eggs into skillet. Cook for 3 minutes for sunny side up or until desired doneness is achieved.
Meanwhile, preheat broiler to high. Arrange tostadas on parchment-lined baking sheet. Spread refried beans over tostadas and sprinkle with cheese. Broil for 2 to 3 minutes or until cheese is melted.
Slide each egg onto tostada. Top with salsa, sour cream, avocado, cilantro and green onion. Serve immediately