Combine sugar, corn syrup and hot water. Heat, stirring until sugar dissolves. Boil without stirring to firm ball stage (244 to 248° F on a candy thermometer; in humid weather cook to 248° F).
Beat egg whites stiff. Slowly add hot syrup, beating at high speed until thick and fluffy. Add salt and vanilla extract. Gently fold in mayonnaise and orange rind. If thicker then desired, fold in 1 or 2 Tbsp more mayonnaise, or 1 or 2 tsp water.Makes 3 cups Source: