Clean and wash leeks, cut into thick slices about 1 cm . Stew in the oil in a saucepan, under cover until tender. Add the washed rice and stew for another few minutes. Pour 500 ml hot water, add salt and leave on low heat to boil for 20-30 minutes. Before you remove from heat, put the butter and pepper. Optional each portion can be served with a few black or green olives.