Transfer the eggs into a bowl and whisk them so that the egg whites and the yolk mix evenly. Add the salt and pepper then mix once more (be careful when adding the salt as the cooked ham already has a high salt content or you can skip it altogether).
Heat the oil in a non-stick pan and add the onions, peppers and ham.
Sauté and cook them for about 5mins on a medium flame. You just need the onions and peppers to cook slightly. Then, transfer them into a bowl.
Add a tablespoon of oil to the same pan (you can use cooking spays too) and pour half of the whisked eggs into the pan. Keep it on a medium flame and cook until the sides of the eggs are cooked and change colour.
On one half of the omelette, spread half of the above cooked ham-veggie mixture.
On the other half of the omelette, spread a tablespoon or more of cheese (I prefer to use mature cheddar cheese).
Let the cheese melt, and then fold the omelette in half.
You can enjoy the omelette on its own or with toast.