Pop!: 40 Recipes from Popcorn Land
Place the popcorn kernels in a large brown paper bag. Add the oil, if using, and shake the bag to coat the kernels.
Fold the top 1 cm (½ in) of the bag over and crease, then repeat two more times. Twist the top corners of the bag to seal.
Microwave the popcorn on high for 2 minutes, listening for the sound of popping kernels. Once the popping has slowed to 2–3 pops a second (this takes roughly 1½ minutes in a 1000-watt microwave), remove the bag from the microwave and immediately pour the popcorn into a large bowl.