Place the avocado in a bowl. Mash with a fork and add the sour cream, lime juice, and chopped cilantro. Season with salt and pepper. Stir well and mix to form a cream. Set aside.
In another mixing bowl, combine the salsa, black beans, corn, scallions, and hot sauce; season with salt and pepper. Mix well.
Take 1 of the tortilla chips and add a small dollop of the avocado cream. Top with the corn mixture. Garnish with a cilantro leaf.
Recipe courtesy of Ingrid Hoffmann, 2008