Preheat oven to 350 degrees F. Line cookie sheet with parchment paper, set aside while making the dough. In a small bowl sift together flour, cream of tartar, and baking soda. Set aside.
In a mixing bowl add sugar and lemon zest. Mix on medium speed for 30 seconds.
Add butter, mix until pale and fluffy, about 1 minute.
Mix in eggs, 1 at a time, and then the lemon juice.
Reduce speed, gradually add flour mixture, and mix until just combine.
Cool cookie dough in the refrigerator for at least an hour. This helps so the cookies don't go completely flat during baking.
Using a cookie scoop; scoop dough 2 inches apart on a parchment lined cookie sheet. Flatten cookies slightly with a spatula.
Sprinkle sanding sugar, then lightly brush with a wet pastry brush, sprinkle with more sanding sugar. Bake cookies until golden brown, between 8 to 10 minutes. Let cool on cookie sheet for 3 minutes then transfer to a cooling rack; let cool completely.
Cookies can be stored in an airtight container at room temperature for 4 days or you can freeze the cookies in freezer bags for up to 3 months.