Prepare 8-10 cups of popped popcorn and pour pecans on top. Set aside for later. 

In a medium pot bring butter, sugar, and corn syrup to a boil. Boil 1 to 1 1/2 minutes. Do not over boil. 

Take off heat and add baking soda, cream of tartar, and vanilla.

Pour over popcorn and mix until fully coated.

Grease hands with vegetable shortening, butter, or oil and shape the coated popcorn into balls before it cools, placing it on a parchment-lined baking sheet. Be careful as the sauce will be hot. Let sit for about 15 minutes before wrapping individual popcorn balls in plastic wrap or sandwich bags.