Cover whole fruit with the water , and simmer for 2 hours in a covered pan until the fruit is completely tender. Cut the fruit in half, scoop out the pips and flesh and boil in 300ml water for 10 minutes. Strain this through muslin into the liquid the oranges were cooked in. Cut the peel into shreds and add to the juice with the sugar. Boil as before. This method is best if using whole frozen oranges.