Heat the oil in a 12-inch nonstick skillet over medium heat. Add the scallion whites and ginger and cook, stirring frequently, until they are softened and fragrant, about 2 minutes.

Transfer the scallion mixture to a large bowl and whisk in the miso and half of the vinegar until a smooth paste forms; wipe out the skillet with a paper towel.

Heat the remaining oil in the skillet over medium-high heat until it shimmers. Add the corn and sprinkle with salt, spreading it into an even layer.

Cook the corn without stirring for 3 minutes — the bottom should be deeply browned and you may hear some kernels starting to pop.

Stir the corn and continue to cook, stirring only once or twice, until the kernels are spotty brown all over, 2 to 3 minutes more. Stir in the mirin and cook until the liquid has completely evaporated, about 1 minute.

Transfer the corn to the bowl with the miso mixture. Add the scallion greens and toss well to coat. Season with the remaining vinegar and additional salt to taste. Serve warm, sprinkled with sesame seeds.