1 stick butter
1 c. brown sugar
1/2 c. white Karo syrup
1/4 tbsp. salt
Pinch of cream of tartar (optional)

Bring to a rolling boil. Boil 2 1/2 minutes. Add 1/2 tablespoon baking soda. Meanwhile have 1 1/2 cups popped popcorn in a large grocery bag. Pour syrup mixture over popcorn. Mix quickly (with a wooden spoon) and fold top of bag closed. Put in microwave and cook 1 1/2 minutes on high. Remove bag and mix thoroughly. Cook again 1 1/2 minutes more. Spread out on cookie sheet to cool.