Lightly spoon flour into dry measuring cups, and level with a knife. Combine 2 cups flour, ginger, baking soda, cinnamon, pepper, and salt. Beat margarine, 1/2 cup granulated sugar, and brown sugar at medium speed of a mixer until light and fluffy. Add molasses, and beat 2 minutes. Add egg and egg white, and beat mixture until fluffy. Stir in the flour mixture until well-blended. Shape the dough into a ball with floured hands; add enough of remaining flour, 1 tablespoon at a time, to prevent dough from sticking. Wrap in plastic wrap; chill 1 hour.
Preheat oven to 375°.
Shape dough into 30 balls with floured hands. Roll balls in 1/4 cup granulated sugar; place 2 inches apart on baking sheets coated with cooking spray. Bake at 375° for 12 minutes. Immediately remove cookies from pans to a wire rack; cool completely.