In 10-inch omelet pan or skillet over medium heat or hot coals, cook corn, peppers and onion in butter until tender but not brown, about 5 to 7 minutes. Meanwhile, in large bowl, beat together eggs and milk with salt, if desired, until blended.
Pour over vegetables. As mixture begins to set, gently draw an inverted pancake turner completely across bottom and sides of pan, forming large soft curds. Continue until eggs are thickened and no visible liquid egg remains. Do not stir constantly. Garnish with pepper rings, if desired.