Place pistachios in food processor and pulse until the pieces are slightly larger than a grain of rice. A few large pieces are fine.
Pour into a small bowl and add currants, zest from one lime and ¼ cup of granulated sugar. Toss to combine and set aside.
In the bowl of a stand mixer with the paddle attachment, beat butter until creamy. Add remaining sugar and beat until slightly pale in color.
Add flour while mixing on low, and then add the lemon extract. Beat until mixed and slightly crumbly.
Add nut and currant mixture and beat on low just to incorporate.
Pour out onto your counter and press together and form into a log, 18 inches long. Doesn’t have to look perfect.
In a small bowl, mix sugar in the raw with the zest of one lime and combine.
Line three cookie sheets with parchment paper.
Cut the log in half with a sharp knife. Then cut each half into thirds. Then cut each third into five pieces. This will yield 30 slices.
Pick up each slice and form into a circle about a half inch thick.
Dip both sides in the raw sugar and place on a cookie sheet. Repeat for the remaining pieces, filling up three pans.
Place all three pans in the refrigerator for about an hour to harden.
Preheat oven to 350 degrees F.
Bake each pan right from the refrigerator to the oven for 12-14 minutes.
The finished cookie will still be soft and just starting to get slightly tan in color. Do not bake longer than 14 minutes, in fact less time is better than more time.
Let each cooked pan sit out of the oven for five minutes. Then slide the parchment sheet with the cookies onto a rack and let cool completely before you attempt to remove them from the parchment. They will harden slightly as they cool.
Once cool, remove from parchment and store in a covered container for up to three days or freeze.