Cream butter in a large mixing bowl; gradually add sugar, beating until light and fluffy. Add egg, egg yolk, and vanilla, beating well.
Combine flour, soda, and salt in a small mixing bowl; add to creamed mixture, stirring well. Divide dough in half; tint one half with red food coloring. Wrap each half in waxed paper; chill 2 hours.
Shape into 6- x 1/4-inch ropes on a lightly floured surface. Place plain ropes and red ropes together, and twist gently. Place on greased cookie sheets, and shape into candy canes. Bake at 350° for 10 to 12 minutes. Cool slightly on cookie sheets, and remove to wire racks. Repeat procedure with remaining dough.