Set a large bowl on the counter to pour your popped kettle corn into.
To a large heavy-bottomed pot (with a lid) add oil and 3 kernels of popcorn. Cover and heat over medium-high heat (medium if your stove runs hot) until you hear all 3 kernels pop.
Add the rest of your popcorn and shake pan for about 10 seconds to coat the kernels. Pour sugar and salt directly over the popcorn. Cover and shake for 3 seconds, rest for 3 seconds, repeat, until popcorn begins to pop steadily.
Once that starts, shake pan mostly continuously, pausing occasionally to listen for breaks in popping. Once there is about a 2 second break between pops, pull from heat. Transfer popcorn immediately to your bowl.
Allow to cool for a couple of minutes (sugar will be VERY hobefore eating. Keep an eye out for unpopped kernels as you eat, and enjoy.