In a large saucepan (with cover), heat the oil and salt over medium/high heat. OPTIONAL:
Add optional seasoning in any combination and to taste.
Put 3 or 4 popcorn kernels into the oil and cover the pan.
When the kernels pop, remove from heat, and add the rest of the popcorn kernels in an even layer. Cover, count 30 seconds (this will bring the kernels up to near-popping temperature).
Return the pan to the heat. Gently shake the pan by moving it back and forth over the burner. Try to keep the lid slightly ajar to let the steam from the popcorn release.
Once the popping slows to several seconds between pops, remove the pan from the heat, remove the lid, and dump the popcorn immediately into a wide bowl. OPTIONAL:
Melt the butter in the now empty, but hot pan. Pour evenly over popcorn.