Cook only on a DRY day! In heavy-bottom pan over medium heat, boil syrup of sugar, water and Karo till close to done (about 10 minutes); will spin a thread to pot. Take candy off heat. Beat egg white with a pinch of salt till you have stiff peaks. In a large bowl, add the hot syrup to the beaten egg white while mixing at a high speed. If syrup starts to harden, pour a little more. When mixture gets stiffer and warmer, can add in a larger stream. Add vanilla extract to candy. Stir by hand until texture dulls (seems like it takes FOREVER). When cool, add nuts (if you add them too soon, the heat pulls the oil out of the nuts and the candy won't harden). Drop by tablespoons onto waxed paper. To expand the recipe, use no less than 2 cups of sugar; if you quadruple, add an extra egg white, especially if eggs are small. Might try stirring in 3 oz. of broken white chocolate before dropping candy (won't melt).