Put 1 tablespoon olive oil, kernels and salt into a large pan. Make sure the kernels are in a single layer.
Cover the pot and heat it over medium high heat. Wait about 30 seconds until you hear popping sounds. Take it from heat and shake the pan moving it back and forth. Put it back on the heat with its lid slightly ajar. Repeat this two or three times in a minute.
When the popping slows down, remove the pot from the heat and wait until you hear no sound, about a minute. Make sure the pot is still ajar.
When there is no popping at all, remove the lid. Drizzle 1 tablespoon olive oil over it, sprinkle cumin, chili powder and black pepper. Stir with a spoon well until all kernels are coated.
Repeat for the remaining kernels.
NOTES
Note: As an alternative seasoning method, you can sprinkle all the spices on the corn kernels when you put them in the pot along with the oil. Give them a good stir with a spoon and then pop.