Spray a sheet of aluminum foil and 2 forks with cooking spray. Combine sugar, water, vanilla, and cream of tartar in a heavy medium skillet over medium-low hear; stirring frequently, cook 10 min.
Using a pastry brush dipped in hot water, wash down any sugar crystals on sides of pan. Stir in pecans. Increase heat to medium. Stirring occasionally, cook 10 min. or until sugar begins to caramelize. Stirring constantly cook 1 to 2 min. until sugar is caramelized and pecans are golden brown (watch very closely to prevent burning).
Spread on aluminum foil. Use forks to separate pecans; allow to cool. Store in an airtight container.