Shuck the corn and remove as much of the silk as you can.
Sprinkle the corn with salt and add it to a sealable bag with the butter.
For the best results, use a vacuum sealer to remove the air from the bag. You can also use the water displacement method (see post above) if you don't have a vacuum sealer.
Use a heavy duty binder clip to clip heavy butter knives to each side of the bag to prevent floating.
Place the bag in the water bath and cook for 30 minutes.
Remove and serve the corn immediately with salt or other seasoning as desired.
Notes
You should always remove the air from the bag to avoid bacteria entering the bag.
The bag should be completely submerged in the water bath to ensure even cooking.
As corn floats, you’ll need to weigh the bag down with something heavy. Floating can cause uneven cooking.
If there is too much air in the bag, you may need to open the bag during cooking, remove the air and reseal it with the vacuum sealer.
You can use frozen corn if fresh is not available. Just add 30 minutes to the cooking time.