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 the pan for a few 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 hot) before eating. Keep an eye out for unpopped kernels as you eat, and enjoy.