Open can of black beans, rinse and drain well. Pour beans onto serving platter and mash coarsely with fork. Spread beans evenly over entire platter. Spread sour cream over top beans. Spoon salsa by the tablespoon over top sour cream layer and then spread gently to coat but not mix into the sour cream. Sprinkle grated cheese over top salsa layer. Top with diced tomatoes. Sprinkle green peppers over top entire dish. Cut avocado in half, open and remove pit. Scoop out flesh with large spoon. Dice into small pieces and sprinkle pieces over top of dish. Squeeze lime juice over avocado. Top with ground pepper. Sprinkle green onions over top entire dish. Sprinkle chopped cilantro over top entire dish. Serve immediately or store covered in refrigerator until ready to serve.