Steps
1. In a bowl, whisk the eggs and season with salt and pepper.
2. Heat a small amount of butter or oil in a non-stick pan over medium heat.
3. Add the diced onions and tomatoes to the pan and sauté until softened.
4. Pour the whisked eggs over the onions and tomatoes, spreading them evenly.
5. Cook the omelette until the edges start to set, then place the cheese slices on one half of the omelette.
6. Fold the other half of the omelette over the cheese to create a half-moon shape.
7. Cook for a few more minutes until the cheese is melted and the omelette is cooked through.
8. Toast the bread slices and spread butter or your favorite condiments if desired.
9. Place the omelette between the bread slices to make a sandwich.
10. Cut the sandwich in half and serve hot.