Key Lime Cookies

1 cup butter
1 1/2 cups white sugar
1 egg
1/2 tsp vanilla extract
3 Tblsp lime zest
4 Tblsp fresh squeezed lime juice
2-3 drops green food coloring
1/2 tsp salt
1/2 tsp baking powder
1 tsp baking soda
1/4 tsp cream of tartar
2 3/4 cups all-purpose flour
1/2 cup sugar for rolling cookies


Directions:
 

Preheat oven to 350 degrees. Cream together butter and sugar until smooth and very fluffy. Beat in egg, vanilla extract, food coloring, lime juice and lime zest. Gradually blend in the dry ingredients. Roll rounded teaspoonfuls of dough into balls, and roll in sugar. Place on greased cookie sheets about 1 1/2 inches apart. Bake 8 minutes until lightly browned. Let stand on cookie sheet two minutes before removing to cool on wire racks.