For breakfast or for dinner, there's nothing like a simple cheese omelet. This American diner style-omelet recipe is quick and easy to make and very satisfying.
Using a fork, beat eggs with 1 teaspoon water until yolks and whites are completely combined and no streaks remain. The water helps incorporate them and steams while the omelet cooks, which puffs it up. Season with 1/8 teaspoon kosher salt and a few cracks of pepper.
Heat butter in an 8-inch nonstick skillet over medium-high until foaming;swirl to coat. When foam subsides, pour eggs into center of skillet. Let stand 10 seconds. Stir eggs with a rubber spatula in a circular motion with one hand while shaking skillet with the other, about 15 seconds. Reduce heat to medium. Working your way around skillet, gather outer set eggs toward center, then tip skillet so runny eggs move to outside edges, about 1 minute. Lightly spread any remaining runny eggs evenly over top and cook until creamy but no longer wet.
Sprinkle cheddar onto far side of omelet. Remove from heat. Tip pan away from you; gently slide spatula under near side of omelet and fold up and over cheese. Slide onto a warm plate. Top with chopped chives and serve, with sliced tomato sprinkled with salt and buttered toast, if desired.