Defrost the raspberries. Heat 150 ml water, sugar and lemon peel until the sugar is dissolved. Bring to the boil and simmer for about 6 minutes. Pour syrup through a sieve and let it cool down. Puree the raspberries and mix with the syrup. Pour everything through a sieve
Place in a bowl and allow to freeze for about 1 hour. Stir well with a whisk. Beat the egg white until stiff. Carefully fold into the frozen mixture. Stir again every 30 minutes for approx. 4 hours until a portionable sorbet is formed
waiting time approx. 7 hours