Crack the eggs into a small bowl and whisk briskly until the mixture is uniform, with a slight froth on top. Season with a pinch of salt and pepper.
Chop your chosen protein—smoked salmon or roast chicken—into small, bite-sized pieces and set aside.
If using vegetables, sauté them in a small skillet with a little oil over medium heat for 2-3 minutes until fragrant and slightly wilted, then remove and set aside.
Add a tablespoon of oil or butter to the skillet and heat over medium until shimmering and hot.
Pour the beaten eggs into the skillet, tilting it slightly to distribute evenly. Let cook undisturbed for 20-30 seconds until the edges start to set and bubble gently.
Sprinkle the chopped protein evenly over one half of the eggs, then add cheese and sautéed vegetables if using. Continue cooking for another 30 seconds until the eggs are just starting to firm up.
Use a spatula to carefully fold the omelette in half over the fillings, pressing gently to seal. Cook for another 1-2 minutes until golden and the cheese is melted.
Gently slide the omelette onto a plate and let rest for a minute. Garnish with freshly chopped herbs for a bright finish.
Slice if desired and serve immediately while warm, with the cheese gooey and fillings flavorful.