Heat a 10-inch, non-stick skillet over high or medium-high heat.
Beat 2 eggs with 2 tablespoons of water and a pinch of salt until smooth in consistency.
As soon as the butter in the skillet is melted, add egg mixture. The mixture should begin setting immediately.
With an inverted pancake turner or spatula, move the eggs from the center of the skillet to the edge so uncooked portions can reach the skillet’s hot surface. Tilt the pan and move it as necessary to keep the entire skillet surface covered in egg mixture.
Pour 1/2 cup of desired mixture (cheese, meat, peppers, etc.) onto the omelet. With a spatula, fold the omelet in half. Invert onto plate.