Set a saucepan of water to the boil and add the rice. Cook until done then drain.
Meanwhile, in a small bowl, beat together the eggs, 1 tablespoon water and salt and pepper to taste.
When the rice is cooked, heat the butter and oil in a non-stick frypan over medium heat. Add the egg and swirl the pan so the bottom is evenly coated. Turn the heat down to medium and cook the omelette, loosening with a spatula as needed, until the bottom is browning and the top is almost cooked.
Transfer the omelette to a warm plate and spoon the drained rice along the middle. Fold the omelette over the rice and drizzle with chilli sauce.