Pour the oil and popcorn into a heavy deep pot. Place over medium heat; cover and shake, moving the pot constantly. Continue cooking the popcorn until the popping slows down, about 3-4 seconds between the pops. Pour into a medium size bowl.
Melt the butter in a small pot. In a small bowl, mix together the vinegar powder and salt.
Drizzle the butter over the popcorn and sprinkle with vinegar powder and salt until the popcorn is coated.