Take out a pot with a large surface area (one that has a matching lid). A 5-inch deep, 9-inches across pot is perfect for 1 cup of popcorn.
Pour in the oil and then add the popcorn kernels. Sprinkle in a bit of sea salt, if desired. Shake the pan around to evenly distribute the kernels and coat them with oil. The pan should be big enough so that the kernels are not over-crowded and/or piled on top of each other.
Turn heat to medium and begin to slide the pot back and forth over the burner. Keep sliding/shaking the pan back and forth to evenly distribute the heat to all sides of the kernels. Eventually (3-5 minutes later), the first kernel will pop. At this point, put the lid on the pan. Keep sliding/shaking the pan back and forth and the other kernels will begin to pop. Keep that pan moving back and forth until the popping slows down and the kernels are all popped. Remove the pan from heat.
Toss popcorn with melted butter and/or other seasonings, and serve immediately.
Notes
A few sweet (dessert) suggested add-ins from RecipeGirl readers: 1. chocolate syrup + peanut butter 2. caramel 3. mix in junior mints, hot tamales, chocolate chips, reeses pieces, m&m's or sugar babies 4. maple syrup 5. melt marshmallows with brown sugar and butter and mix in
And the savory suggested add-ins from RecipeGirl readers: 1. sea salt + freshly ground pepper 2. maple and bacon 3. Parmesan + freshly chopped rosemary 4. butter + cajun spice + brown sugar 5. fajita seasoning 6. cayenne pepper or tabasco 7. Parmesan and pepper 8. butter-flavored olive oil 9. ranch seasoning 10. white truffle oil + Parmesan 11. brewers/nutritional yeast 12. chili oil + garlic powder + curry powder 13. cheese packet from a macaroni & cheese box 14. Old Bay Seasoning 15. Dill pickle seasoning (not sure I've ever seen that) 16. Meat tenderizer (what?? Really?)