Mix sugar and cornstarch in a medium sauce pan. Gradually whisk in water and cook over medium heat. Stir constantly until mixture thickens and boils. While constantly stirring, boil for one minute.
Gradually stir half of the hot mixture into the egg yolks. Blend back into mixture in pan. Boil and stir one minute. Remove from heat and stir in butter, lemon peel, and juice.
For the Sauce
Combine sugar and water in a small saucepan. Cook over high heat, stirring constantly, and bring to a boil. Reduce heat, and simmer until sugar is dissolved.
Remove from heat, and allow syrup to cool completely. Place raspberries and syrup in the jar of a blender; puree until smooth. If you want to remove the seeds, pour through a fine sieve. Drizzle sauce over the lemon pudding and serve.