Keep popcorn hot in a 300-to-350-degree-Fahrenheit oven. Spread margarine in the bottom of saucepan.
Combine sugar, water, corn syrup, vinegar and salt. Cook and stir to hard-ball stage or until a candy thermometer registers 250 degrees Fahrenheit. Stir in vanilla.
Slowly pour over hot popped corn. Stir just until mixed.
Grease hands/gloves; shape into three-inch balls.
Photography by Peri Photography