Grind pecans in blender or food processor. Beat butter with sugar, salt and vanilla. Beat in ground pecans and flour. Shape into ¾ inch balls. Place on ungreased baking sheets. Bake at 325 degrees for 15 minutes. Allow to cool 5 minutes. Place powdered sugar in small paper or plastic bag (a small Ziploc bag works really well). Drop warm cookies, a few at a time, into bag. Shake gently. Cool sugar coated cookies on wire rack. Shake again in powdered sugar if heavier coating is desired. (I usually don’t do this.) Makes about 4 dozen. (I usually roll out all 48 and make adjustments to sizes of balls. Dough can be made in advance and stored in the refrigerator. I use half sheet pans and fit 48 per pan in 8 rows of 6.)