Preheat oven to 400°F.
In a large bowl, beat eggs with oil, vanilla, zest and sugar.
In a separate bowl, combine flour, baking powder and salt.
Stir flour mixture into egg mixture.
Drop dough by the tablespoon full onto parchment paper covered cookie sheet.
Grease the bottom of a glass with butter or cooking spray. Dip glass into colored sugar then gently press on ball of dough until dough is ¼-inch thick. Repeat on each ball of dough.
Bake 5-6 minutes or until edges of cookies start to turn golden brown.