Preheat oven to 325-f. In a mixing bowl, cream together the butter, oil, and sugars. Mix in the eggs, vanilla, and salt.
Add 2 cups of flour and mix. Add baking soda and cream of tartar and mix again. Stir in remaining flour until combined. Stir in pecans.
Roll dough into 1 inch balls and roll each ball in sugar. Place the cookies 2 inches apart on a parchment lined baking sheet and bake for 10-12 minutes or until the edges are golden.
Allow cookies to cool on the sheet for a few minutes before transferring to wire racks to cool completely. Store in an airtight container.
Notes
Pecan Sandies freeze well after baking. Recipe from Back For Seconds