Wash the rice with cold water in a bowl. Strain and repeat twice. Put a fairly large amount of water in a big pan and bring to the boil. Add salt if you prefer. Tip the rice into the boiling water and stir round. Boil vigorously for about 20-25 minutes stirring occasionally. Strain with a sieve. Rinse with water boiled in a kettle. Your rice is ready! Optional: Put the butter into the serving bowl.