Set oven rack on top position and preheat to 375F degrees. Line a cookie sheet with parchment paper.
In a medium bowl, whisk together flour, baking powder and salt. Set aside.
In a mixing bowl, beat butter and sugar at medium speed until light and fluffy. Add the sour cream, egg and vanilla, combining well between each addition.
Gradually add flour mixture and beat until well combined. (Do not overbeat it, though)
Cover the cookie dough and chill for one hour.
Combine cranberries, walnuts and orange rind.
Turn dough out onto a lightly floured surface and roll into a 10-inch square. (About 1/4 inch thick.)
Sprinkle with cranberry mixture, leaving a 1/2-inch border on 2 opposite sides.
Roll up dough, jellyroll fashion, beginning at a bordered side. Cover and freeze 6 hours or up to 1 month.
Cut roll into 1/4-inch thick slices. Place slices on cookie sheet. Bake on top oven rack at 375 degrees for 14 to 15 minutes or until lightly golden browned at the edges.
Remove to wire racks to cool completely.
Makes about 30 "pretty" cookies plus extra from the roll ends that aren't as nice looking, but every bit as delicious.