Unfold the pastry sheet on a lightly floured surface. Brush the pastry with the egg mixture. Sprinkle with the cheese and cilantro to within ½ inch of the edge. Starting at a long side, roll up like a jelly roll. Press the seam to seal. Cut the pastry roll into 20 (½-inch) slices. Place the slices, cut-side down, onto 2 baking sheets.
Bake for 15 minutes or until the pastries are golden brown. Gently flatten the hot pastries with a spatula. Let cool on baking sheets on wire racks for 10 minutes.
MAKE THE TOPPING:
In a medium bowl, combine the corn, beans, onion, red pepper, jalapeño, cumin and lime juice.
MAKE THE GUACAMOLE:
In a medium bowl, use a fork to mash the avocado. Stir in the sour cream and lime juice. Season with salt and pepper, to taste.
ASSEMBLE THE BRUSCHETTA:
Top each pastry with about 2 teaspoons of guacamole and 1 tablespoon of the topping mixture. Garnish with additional fresh cilantro, if desired.