Preheat oven to 350°. Combine granulated sugar, brown sugar, butter, and vanilla in a large bowl; beat with a mixer at medium speed until fluffy. Add egg; beat just until blended. Beat in flour, baking soda, and salt.
Beat black pepper into cookie dough at medium speed. Stir in strawberries and pistachios. Drop dough by tablespoonfuls 2 inches apart on parchment paper-lined baking sheets. Bake 10 to 12 minutes or until lightly browned.