1. Toss the dried fruit and the 2 tablespoons (20g) of flour together in a small bowl and set aside.
2. In the bowl of a stand mixer, or by hand, beat together the butter and sugar until smooth and creamy, about one minute. Add the eggs, one at a time, then the vanilla, beating until incorporated.
3. In a separate bowl, whisk together the 1 1/2 cups (210g) flour, polenta, baking powder, and salt.
4. Mix the dry ingredients into the beaten butter mixture until incorporated, than stir in the dried fruit.
5. Form the dough into a rectangle 4- by 7-inches (10 by 18 cm), wrap in plastic, and chill the dough for about an hour, or until it’s firm enough to handle.
6. Divide the dough in two, lengthwise, and roll each piece of dough on a lightly floured surface into a smooth cylinder 7-inches (18cm) long. Wrap the cylinders and freeze until ready to bake.
(If you prefer to bake the cookies right away, pinch of pieces of dough about the size of a small unshelled walnut, and roll into balls. Place them evenly spaced on the prepared baking sheet and press them down gently with your hands to flatten them partially.)
7. To bake the cookies, preheat the oven to 325ºF. (170 ºC)
8. Line two baking sheets with parchment paper or silicone baking mats.
9. Slice the cookies into 1/4-inch (.75cm) slices and place them evenly spaced on the prepared baking sheets. (The dough is easier to slice when frozen, but if it’s too firm or crumbles when you cut it, let it sit out on the counter until it reaches a good consistency.)
10. Bake the cookies for about 12 minutes, rotating the baking sheets midway during baking, until the cookies are very light brown on top. Remove the oven and let cool completely.