Place the popcorn kernels in a brown paper lunch bag.
Add the olive oil and salt to the bag.
Fold the top of the bag over twice to keep it secure.
Gently shake the bag so that the kernels are evenly coated with oil and salt.
Put the bag upright in the microwave.
Microwave on high for 2 to 3 minutes, or until there is a 5-second gap between pops.
Once popping stops, carefully remove the bag from the microwave to avoid any steam burns.
Open the bag slowly to let the steam escape.
Pour the popcorn into a large bowl.
Add additional salt or melted butter if desired.