place flour in a large bowl, cut in butter until crumbly, stir in sour cream, wrap in plastic warp. and refrigerate for 1 1/2 hours. or until easy to handle.
in a small bowl, beat egg white, and vanilla on medium speed until soft peeks form. fold in pecans.
divide the dough into 4 portions . roll into 12" by 6" rectangle, place on an ungreased baking sheet. spread a fourth of the egg white mixture lengthwise down the center. fold in sides of pastry to meet in the center, repete.
bake at 375 for 18-20 minutes or until lightly browned.combine confectioners sugar, and milk mix well, drizzle over warm pastries.