PREHEAT oven to 350° F.
COMBINE flour and powdered sugar in medium bowl. Cut in butter with pastry blender or two knives until crumbly. Press onto bottom and 1-inch up sides of ungreased 13 x 9-inch baking pan.
BAKE for 25 minutes.
PLACE cream cheese, eggs, evaporated milk, granulated sugar, flour, lemon juice, lemon peel and food coloring in blender container; cover. Blend until smooth. Pour into partially baked crust.
BAKE for additional 15 minutes or until set. Cool in pan on wire rack. Spread sour cream over top; refrigerate. Cut into bars. Garnish as desired.