Set a medium saucepan over high heat and add 30ml (2 tablespoons) of neutral oil along with 2 popcorn kernels. Cover the pot and wait until both kernels have popped. Add the remaining kernels, cover, and shake the pot continuously until all have popped and you hear a 2-3 second gap between popping sounds. Transfer the popped popcorn to a large bowl. Set aside.
In a small saucepan, melt the butter over medium heat. Once the butter is melted, add the miso paste and the garlic. Whisk until thoroughly combined and the miso is dissolved in the butter.
Pour the miso butter over the popped popcorn and stir until it is even distributed over the popcorn. Season generously with black pepper and serve.