Mix sugar, oil, chocolate and vanilla. Mix in eggs, one at a time. Stir in flour, baking powder and salt. Cover and refrigerate at least three hours.
Heat oven to 350 degrees. Drop dough by teaspoonfuls into powdered sugar; roll around to coat. Shape into balls. Place about 2 inches apart on greased cookie sheet. Bake until almost no indentation remains when touched, 10 to 12 mintues.