Remove the husks and silks from the corn. Break the ears in half if necessary so they fit in your pot.
Fill a large pot with 20 cups of water. Bring it to a rolling boil over high heat. Add a teaspoon of salt if desired, but note that salt may slightly toughen the corn.
Add the corn to the boiling water. Cover the pot, reduce the heat to medium, and simmer for 7–10 minutes. Cook time may vary depending on the size and freshness of the corn. Kernels should be tender and plump.
Using tongs, carefully remove the corn from the water. Serve hot with butter and a sprinkle of flaky salt if desired.