Heat the milk and onion, then remove onion. Chop the corn and cook it with the water 20 minutes. Melt the butter, add the flour, and when bubbling, add first ⅔cup, then the rest of the milk gradually; cook till slightly thickened. Add this mixture to the corn and season with salt and pepper. If you wish rub the corn through a sieve. Serve hot, with crackers.