Wash rhubarb; discard leaves and dice stems. Add water, cover and cook slowly until rhubarb is soft. Mix together 1/2 cup of the sugar and a tablespoon of the cornstarch and stir into the rhubarb; stir constantly over low heat until sauce is thickened, then remove from heat. Mix remaining cornstarch, sugar and salt in saucepan, add milk and cook over direct heat with constant stirring, until mixture boils and thickens. Slowly stir into the beaten eggs and cook over hot water, stirring constantly for 2 minutes. When both custard and rhubarb sauce are cooled, stir the rhubarb into the custard. Serve chilled. 5 servings.