2) In a medium bowl, whisk together the plain and wholemeal flours, the baking powder and salt. In a large bowl beat together the sugar, honey, eggs, oil, zest, lemon juice and vanilla essence until well combined.
3) In batches add the dry ingredients until the mixture forms a dough. Stir in the pistachios.
4) Transfer the dough to a floured work surface and knead several times. Shape into a log about 25-cm long and 8-cm wide. Transfer to a parchment lined baking sheet and bake for 25 minutes.
5) Transfer to a wire rack and let cool for 15 minutes. With a serrated knife, cut 1-cm diagonal slices. Arrange on the baking sheet and bake 10 minutes. Turn the cookies over and bake the biscotti until golden 5 to 10 minutes longer. Transfer to a wire rack to cool.