Preheat oven to 375 degrees. Line 2 baking sheets with parchment paper. Whisk the flour, baking soda, and salt in a medium bowl.
In a large bowl beat the butter until fluffy. Add the sugars and beat on medium-high speed until fully incorporated and fluffy; about 3 minutes. Beat in the egg, lemon zest, lemon juice and vanilla.
Reduce the speed to low; beat in the flour mixture in three batches, alternating with the sour cream.
Using your hands, roll the dough into 16, 1 1/2 inch balls. Arrange on baking sheets; sprinkle with sanding sugar. Bake until the edges are set and slightly browned. 12-15 minutes. Let cool 5 minutes before removing from the pans to a rack. Cool completely.
Sandwich the ice cream between the cookies. Freeze until firm; about 3 hours. Take the frozen cookies out of the freezer for 10 minutes before serving.