In small bowl, whisk together flour and salt. In medium-size bowl, beat butter until creamy, 1 minute. Beat in sugar until fluffy, 2 minutes. Beat in yolks and vanilla. Stir in flour mixture until dough comes together. Divide into quarters.
Roll each quarter of dough into 6-inch log, 1 inch thick. On cutting board, spread pecans in rectangle, 7 x 5 inches. Roll 2 of the logs in pecans to evenly coat edge. Wrap each log in plastic wrap; refrigerator. Repeat with red sugar and remaining 2 dough logs. Refrigerator 2 hours or overnight.
Heat oven to 350°F. Unwrap logs. Cut each in 16 slices, about 1/4 inch thick. Transfer to ungreased baking sheet.
Bake cookies in 350°F oven for about 14 minutes or until just golden around edges. Remove cookies from sheet to wire rack; let cool completely. Store in an airtight container for up to 2 weeks.
