Preheat oven to 350.
Line a heavy large baking sheet with parchment paper.
Whisk the flour and baking powder in a medium bowl to blend.
Using an electric mixer, beat the sugar, butter, lemon zest, and salt in a large bowl to blend.
Beat in the eggs, one at a time.
Add the flour mixture and beat just until blended.
Stir in the pistachios and cranberries.
Form the dough into a 13 inch long, 3 inch wide log on the prepared baking sheet.
Bake until light golden, about 40 minutes.
Cool for 30 minutes.
Place the log on the cutting board.
Using a sharp serrated knife, cut the log diagonally into - to -inch thick slices.
Arrange the biscotti, cut side down, on the baking sheet.
Bake the biscotti until they are pale golden, about 15 minutes.
Transfer the biscotti to a rack and cool completely.
Keep stored in an airtight container for up to a week.