In a small saucepan on medium high heat, dissolve sugar and water along with the zest until the sugar has completely dissolved. Remove from heat and let cool. Add lemon juice. Strain and chill, either in the refrigerator, or by placing in a metal bowl over an ice bath.

Once the mixture has thoroughly chilled, freeze in your ice cream maker according to instructions. Meanwhile beat egg white to a froth. A couple of minutes before it is finished, add beaten egg white.

Place sorbet in an airtight container and freeze until ready to serve.

Scoop out preferably with a melon-baller. Garnish with mint. Makes 2 1/2 cups.