Mix sugar, corn syrup and water together and cook, stirring constantly, until tested by dropping a teensy bit into cold water. When done, it will crack against the side of a cup (270 degrees on a candy thermometer).
Beat the egg whites until very stiff.
Add the salt and vanilla to the egg whites.
When the syrup is ready, pour very slowly into the stiffly beaten whites. Beat until creamy.
Add 1 cup chopped walnuts.
Pour into a buttered 8x8 inch pan, or you can drop them my teaspoonful onto waxed paper. Let cool.