Crack the eggs into a mixing bowl. Add a pinch of salt and pepper, then whisk vigorously until the eggs are slightly frothy and well combined.
Heat your non-stick skillet over medium-low heat. Add the oil or butter and wait until it shimmers and begins to crackle gently, emitting a faint toasted aroma.
Pour the beaten eggs into the hot skillet. Let them sit undisturbed for about 10 seconds, then gently tilt the pan in a circular motion to distribute the eggs evenly across the surface.
As the eggs start to set around the edges (after about 30 seconds), sprinkle the cooked protein evenly over one half of the omelette. Add cheese and sautéed vegetables now if using, allowing them to melt slightly into the eggs.
Check the edges—once they turn a light golden brown and the top is mostly set but still slightly moist, gently fold the omelette in half over the fillings using your spatula. Press lightly to help it seal and finish cooking for another 30 seconds to a minute.
Slide the omelette onto a plate and let it rest for about 1 minute. This helps the fillings settle and keeps the omelette moist inside. Garnish with fresh herbs, then serve immediately while warm and fluffy.
