Preheat oven to 350F. Place pistachios on a baking sheet and toast until fragrant, about 15 minutes. Cool completely, coarsely chop. Increase oven heat to 375F. Lightly grease or butter a baking sheet and dust with flour, tapping out excess, or spray with nonstick cooking spray.

In a large bowl, sift together flour, baking soda and salt. Add sugar, chopped nuts, cranberries and crystallized ginger, if using. Stir to combine. In a small bowl, beat together egg yolk and eggs with an electric mixer. Stir in vanilla and orange zest. Pour egg mixture into flour mixture and mix with electric mixer on low speed until just combined. The dough will be stiff.

Turn dough out onto a lightly floured work surface and divide into thirds. Shape dough into three 18-inch long, 1/2-inch thick logs. Arrange logs on prepared baking sheet several inches apart and brush lightly with lightly beaten reserved egg white. Bake for 20 minutes.

Remove from oven and let cool slightly on baking sheet. Reduce oven heat to 225F. While still warm, cut logs into diagonal slices about a half inch wide. Lay slices cut-side down on baking sheet and return to oven. Bake until crisp and brown, 20-30 minutes.