3 tablespoons neutral oil, such as grapeseed or sunflower
1/3 cup popcorn kernels
1 cup toasted pecans (see Tip)
1/2 cup maple syrup
6 tablespoons unsalted butter
1/3 cup light brown sugar
1/4 teaspoon fine sea salt, plus more to taste
1/4 teaspoon vanilla extract
1/8 teaspoon baking soda
Heat oven to 300 degrees, and line a rimmed baking sheet with parchment paper or a silicone baking sheet.
In a large pot with a tight-fitting lid, heat oil and 3 popcorn kernels over medium-high with lid on top. When kernels pop, add remaining kernels to pot, lower heat to medium-low, and crack the lid open a sliver, facing away from you, to release steam. (Alternatively, you could cover the pot with a mesh deep-frying screen, or an upside-down colander or strainer.) Cook, shaking the pot occasionally, until the popping stops.
Transfer popcorn to a heatproof bowl, discarding any unpopped kernels. Add nuts to bowl.
In a medium pot, bring maple syrup, butter and brown sugar to a boil. Cook, stirring constantly, until butter and sugar have melted (the mixture should be foamy). Continue cooking, stirring constantly, until the mixture reaches 240 degrees on an instant-read thermometer. Remove from heat, and stir in salt, vanilla and baking soda. (Mixture may bubble up.)
Immediately pour hot syrup over popcorn mixture, and use a spatula to mix it well. Scrape popcorn onto prepared baking sheet in one layer. Bake, rotating the pan after 15 minutes, for 25 to 35 minutes. You’ll know it’s done when you can remove a piece of the popcorn, and after letting it cool for about a minute, it’s crisp when you bite into it. Taste and sprinkle lightly with more salt if you like. Let cool before serving.
Tip: To toast pecans, spread them in one layer on a baking pan and bake at 350 degrees until they darken slightly at the edges and look golden inside if you break one in half, 8 to 13 minutes. Stir the nuts once or twice as they bake for even cooking.