Heat oil in a pan and add the onions, green chillies and fry for two to three minutes till the onions are golden. Then add the tomato and stir fry for 2 to 3 minutes.
Meanwhile beat the egg whites till stiff and then add the yolks. Beat till fluffy and well blended.
Now add the sauted onion-tomato mixture and coriander leaves. Season with salt and pepper.
Heat 1 tsp ghee in a pan and pour the beaten egg mixture. Tilt the pan to spread the egg mixture.
Now reduce heat to low and allow the omelette to cook. Once the egg omelette is set on one side, turn the omelette and allow it to cook on the other side too.