Wash the rice and cook according to pack instructions in lightly salted water with the diced carrots. About 5 minutes before it's ready, tip in the frozen peas.
While the rice is cooking, heat the oil in as mall frying pan (about 20cm) and lightly beat the eggs with a little salt. Pour the eggs into the pan to coat the base, and cook until almost set as a thin omelette - this should take about 2-3 minutes. Flip the omelette and cook for a few seconds more, then slide it out of the pan and roll it up into a sausage shape. Keep warm.
Melt the butter in a wok or large frying pan and sauté the spring onions for 1 minute. Fluff up the rice mixture with a fork (there should be no cooking liquid left). Tip into the wok with the soy sauce and a little salt and freshly ground black pepper, then stir fry for 2 minutes.
Divide half the rice between two bowls, cut the omelette crossways into strips and scatter over the top. (Keep the remaining rice in a cool place for later.)