In a large, heavy-bottomed pot, warm the coconut oil over medium heat. To test if the oil is hot enough, add two or three popcorn kernels and cover with a lid. Once those kernels pop, remove them, and the oil is ready for the remaining kernels.
Carefully pour the remaining popcorn kernels into the pot and cover it tightly with the lid. Gently shake the pot back and forth over the heat to prevent the kernels from burning. Listen for the popping to slow down, approximately 3-5 minutes—once it's about 2-3 seconds between pops, remove the pot from the heat.
In a small mixing bowl, combine the sweet chili sauce, freshly squeezed lime juice, lime zest, sea salt, and chili powder (if using). Whisk together until all the ingredients are well blended and the mixture is smooth.
Transfer the freshly popped popcorn to a large mixing bowl. Drizzle the prepared sweet chili lime sauce evenly over the popcorn. Gently fold the popcorn with a spatula or wooden spoon until it is evenly coated in the sauce.
If you enjoy a touch of sweetness, sprinkle the powdered sugar over the coated popcorn. Carefully toss again to incorporate the sugar evenly throughout.
Pour the popcorn into a large serving bowl or portion it into fun individual bags for snacking.
Notes
Consider garnishing with extra lime zest for color.