Bring 2 cups sugar and 1 cup water to a boil in a medium heavy saucepan, stirring until dissolved. Boil until amber color develops, 20 to 25 minutes. Remove from heat and quickly add 2 cups pecans and 1/8 tsp. each salt and cayenne pepper. Before mixture hardens spread evenly on a lightly oiled sheet until cool. Break into pieces and serve as a snack or on desserts and salads.