A little bit of steam ensures that you'll never have an under- or overcooked egg white again.From the book "Mad Hungry," by Lucinda Scala Quinn (Artisan Books).
Heat a small cast-iron or nonstick skillet over medium-high heat. Add the butter and swirl it to coat the skillet. Immediately crack the egg into the skillet. Add the water to the pan, reduce the heat to medium low, cover, and cook for 1 minute. Remove the egg from the pan immediately. Season to taste with salt and pepper and serve.