Bring the water, sugar and vinegar to a boil in a large pot. Gently add the husked corn, submerging all the ears in the water the best that you can. Bring the water to a full boil again. This is important! It may take a few minutes for the water to come back to boiling temperature; have patience and persevere.
Once the water is at a full boil, cover the pot, remove from the heat and let the corn sit in the hot, steaming water for 10 minutes. (The corn can stay in the water for up to an hour before serving.)