Preheat oven to 350 degrees F.  Line 2-3 baking sheets with parchment paper.  Set aside.

Using a standing or hand-held mixer, cream butter and sugar together until light and fluffy.  In a small bowl, whisk together sour cream, lemon juice and zest.  Stir into the butter mixture until evenly combined.  Add all-purpose flour, baking soda and salt.  Stir until just combined.  Dough will be soft.  Drop dough by tablespoons, or use a #30 ice cream scoop, onto prepared baking sheets about 2-inches apart.  Bake dough for 16-19 minutes or until light golden brown on the edges.  Remove sheets to wire racks to cool.

In a food processor or blender, combine 1/2 c. granulated sugar, lemon extract or oil, and yellow food coloring.  Sift sugar mixture over the cooled cookies.  Store cookies in an air-tight container at room temperature for up to 5 days, or freeze for up to 3 months.