Preheat oven to 350 degrees and position a rack in the center. Lightly grease a baking sheet with parchment paper and set aside.
Place the raisins in a small bowl and toss them with the Vin Santo and set aside
Spread the almonds and anise seeds evenly on a baking sheet and toast them in the oven until they are light golden brown and aromatic, about 12 minutes. Remove them from the sheet to cool.
In a medium bowl, whisk the flour, polenta, baking powder, baking soda and salt together to combine them thoroughly.
Place the eggs, egg yolk and sugar in the bowl of an electric mixer fitted with the paddle attachment and beat together for a minute. Beat in the butter and lemon zest briefly to combine.
Add the dry ingredients to the bowl and beat to moisten them, then add the almonds and anise seeds and beat to form clumpy dough. Add the raisins and their liquid and beat until the dough comes together.
Divide the dough in half and with lightly floured hands, shape it into two logs about two inches wide and 14 inches long, evenly spaced, on the prepared baking sheet. Lightly beat the reserved egg white and use a pastry brush to glaze the surface of the logs.
Bake the logs for 14 to 16 minutes, or until they are firm to the touch, lightly brown and cracked. Remove the sheet from the oven and allow the logs to cool completely on the baking sheet. Lower the oven temperature to 225 degrees.
When the logs are cooled, slice the biscotti into ½ inch oblongs. Rearrange them on the baking sheet, cut side up. Toast the biscotti until they are dried and crisp, about 20 to 25 minutes. Allow them to cool completely on the baking sheet. Store in an airtight container for up to two weeks.
Makes about 40 cookies