1 cup butter, softened
1 cup granulated sugar
1 cup firmly packed light brown sugar
2 large eggs
3 teaspoons grated lime rind
3 tablespoons fresh lime juice
3 cups all-purpose flour
1/2 cup whole wheat flour
1 teaspoon baking soda
1/2 teaspoon salt
1 cup toasted unsweetened coconut
Beat butter and sugars at medium speed with an electric mixer until fluffy. Add eggs, 1 at a time, beating well after each addition. Add grated lime rind and lime juice, beating until blended.
Combine flour, baking soda, coconut, and salt; gradually add to butter mixture, beating just until blended.
Divide dough into 3 equal portions; roll each portion on wax paper to a 12-inch log. Cover and chill 8 hours.
Cut each log into 1/2 inch slices (about 28 slices), and place on lightly greased baking sheets.
Bake at 350º for 12 to 14 minutes or until edges are lightly browned. Remove to wire racks to cool.