Preheat oven to 450 degree F. For shortcakes, in a medium mixing bowl stir together flour, the 2 tablespoons sugar, and baking powder. Cut in the butter until mixture resembles coarse crumbs. Make a well in the center of the dry mixture.
In a small mixing bowl stir together the egg, half-and-half, and lemon peel. Add egg mixture all at once to dry mixture. Using a fork, stir just until moistened.
Turn the dough out onto a lightly floured surface. Gently knead the dough for 10 to 12 strokes or until dough is nearly smooth. Pat the dough into a 6-inch square. Using a floured knife, cut the square into nine 2-inch squares. Then cut each square diagonally in half.
Place triangles on an ungreased baking sheet. Brush the tops with beaten egg white; lightly sprinkle with coarse-grain sugar or additional granulated sugar. Bake for 8 to 10 minutes or until golden. Remove shortcake triangles from baking sheet; cool on a wire rack.
Meanwhile, in large mixing bowl toss together the strawberries, raspberries, the 1/3 cup sugar, Grand Marnier or orange juice, and 4 teaspoons of the snipped mint. Cover and place in refrigerator to chill up to 1 hour. For each serving, spoon berry mixture onto a dessert plate. Place three shortcake triangles on berry mixture. Top with whipped cream and garnish with remaining mint. Makes 6 servings.