In a large bowl or pot, combine 6 c of water with 1 tbsp of Kosher salt. Submerge corns completely under the water and let them marinade for 15 minutes.
Turn on your grill or pre heat oven to 450F.
Take those corns out of lightly salted water and brush with vegetable oil then put on the grill. If you're using oven, grill for 10 minutes, then turn the corn and cook for another 10 minutes. The corns will be lightly charred.
In a mean time, in a cooking pan, add 2 oz of vegetable oil and heat on medium high heat. When oil is hot enough, add chopped onion and stir for 5 seconds, immediately turn off the heat and let onions carry over cooking for a minute or so. Remove the pan off the heat completely.
Optional: you can eat spam directly from the package or you can quickly cook them with a little bit of oil over medium high heat.
When grilled corns are done, take them out of the oven. Immediately grate cheese on top of corns so they can be melted quickly. Add scallion oil followed by cubes of spam. Enjoy!