Preheat the oven to 425 F. Line two baking sheets with parchment.
In a medium bowl, combine the flour, dried cranberries, and chopped walnut pieces. Keep it aside.
In a large bowl or in the bowl of the mixer, cream together the butter and sugar.
Add the sour cream, salt, baking powder, orange zest, and vanilla and mix well.
Now add the flour mixture in batches and mix well after each addition.
Take a heaped tablespoonful of dough and place them on the prepared baking sheet leaving about 2 inches space between the cookies.
With a flat bottomed glass dipped in sugar, gently press down on each dough mound to flatten it slightly. Don't flatten the cookies too much as they won't be soft and chewy. Leave them about ½ inch thick.
Bake the cookies for about 6 to 7 minutes or just until the sides of the cookies begin to turn brown. Do not over-bake the cookies as again they will lose their soft and chewy texture. The cookies will remain very soft when you take them out of the oven.
Let the cookies cool down for at least 5 minutes in the pan before you transfer them to a cooling rack to cool completely.