Heat 12-inch nonstick skillet over medium heat. Brush one side of each sandwich with oil. Place 2 sandwiches in skillet, oil side down; cook 1 to 2 minutes. Brush tops of sandwiches with oil; turn. Cook 1 to 2 minutes or until golden brown. Repeat with remaining two sandwiches and oil. Cut sandwiches diagonally. Garnish with additional cilantro, if desired.