Stir together chicken, hot sauce, green onions, and freshly ground black pepper in a medium bowl. Spoon 2 tsp. chicken mixture in center of each wonton wrapper. Moisten edges of each wonton with water; fold corners over mixture to form a triangle. Press edges to seal. Heat olive oil in a large nonstick skillet over medium heat. Cook wontons, 12 at a time, in hot oil 2 minutes or until golden. (Do not turn.) Add water; cover and cook 2 more minutes. Transfer to a parchment paper-lined baking sheet, and keep warm in a 200° oven until ready to serve.