Flancati

1 cup butter
1 cup granulated sugar
¼ cup sour cream
3 tablespoons dark rum, rum extract, or vanilla
2 eggs
2 tablespoon vinegar
pinch of salt
2 to 2-1/2 cups all-purpose flour
vegetable oil for frying
vanilla sugar for dusting

Cream butter and sugar until light and fluffy. Beat in sour cream, rum, eggs, vinegar, and salt. Gradually add in the flour. Knead dough until it is smooth. Cover and refrigerate for 1 hour. Roll out dough between two pieces of wax paper until very thin, at least ⅛" thick. Carefully remove the top sheet of wax paper. Cut the dough into rectangles, 2" x 10 ". Make two cuts in each rectangle, parallel to the shorter edge 4" in from both edges. Pick up one edge and pass it through cut on the opposite side, pulling the dough part way through. Do the same with the other side. Heat oil to 375F. Fry cookie in small batches until golden brown. Drain on paper towels. Dust with vanilla sugar.