Have a large baking sheet lined with parchment paper or a large bowl set aside and ready.
Heat the oil in a large pot over medium heat. Add a few test kernels to the oil and cover with the lid.
When they start to pop, add the popcorn kernels, sugar, and ½ teaspoon salt, and stir together just until evenly combined. Cover with the lid.
Quickly stir every 30 seconds until the kernels start to pop. Once popping, constantly shake the pot, removing it from the heat every few seconds and then returning to the heat for a few seconds. (This will help keep the sugar from burning.) Continue shaking on and off the heat until the popping mostly stops, about 3 minutes.
Immediately pour out onto the baking sheet or into the bowl and sprinkle with the remaining ¼ teaspoon salt. Let cool for a minute then toss. Taste and sprinkle with additional salt if desired. Pick out any unpopped kernels that you can find. Serve warm, or let cool completely and store in an airtight container for 3 to 4 days.
Notes
Unlike plain popcorn, any unpopped kernels in kettle corn may not fall to the bottom and instead stick to other popped kernels. Be on the lookout for any as you eat it or if serving the popcorn to children.
You can season your popcorn with cinnamon or a baking spice blend by sprinkling it over the hot popped corn and tossing it to combine. Or, for a spicy twist, add an ⅛ teaspoon of cayenne pepper to the pot with the sugar and salt.
Swap the white sugar for brown sugar for a more caramelized flavor.
Make sure you use a large enough pot to hold all the popcorn once popped and space for the popcorn to move around when you shake it. You also want a pot that’s not too heavy, so you can easily shake the pot.
Keep in mind that this recipe moves fast. Popcorn pops quickly, and you must keep it moving to prevent the sugar from burning.
The oil needs to be hot before you add the rest of the popcorn kerns to the pot. If you add all the kernels into the pot at once, you risk them burning.