Heat oven to 400. Grease a 9" square pan.
For crust: Put flour, sugar and salt in a food processor and pulse until blended. With the processor running, gradually add butter through the feed tube; process until blended. Turn out into prepared pan and gather dough. Flatten and press evenly over the bottom of the pan, forming a 1/2" edge up the sides of the pan. Bake for 10 minutes.
For filling: Stir brown sugar and flour in a medium bowl until blended. Add corn syrup, eggs and vanilla; whisk until well blended.
Spread pecans in an even layer over the partially baked crust. Pour filling over pecans.
Reduce oven temperature to 350. Bake for 25 minutes or until filling is firm. Cool on a wire rack before cutting into bars.