In a small bowl, whisk together flour, baking soda, and salt. Set aside.
With an electric mixer, beat butter and sugar until well combined, 1-2 minutes.
Mix in egg and vanilla.
Stir in flour mixture.
Stir in cranberries and pistachios.
Form dough into a log.
Wrap in parchment paper.
Cover in plastic wrap.
Refrigerate until firm, at least 2 hours.
Heat oven to 350 degrees F.
Line 3 sheet pans with parchment paper. Set aside.
Remove dough from refrigerator.
Use a serrated knife to slice into 1/4" slices.
Place cookies on prepared pans.
Bake for 8-10 minutes, until just starting to color.
Remove from oven and allow to cool on pans.