Directions:

Line two baking sheets with wax paper. 

In a medium saucepan over medium-high heat fitted with a candy thermometer stir together the sugar, corn syrup and water until just combined. Bring the mixture to a boil and then stop stirring. Continue to boil until the mixture reaches the hard ball stage. 

While the sugar boils, in a large bowl whisk together the egg whites and cream of tartar with an electric mixer until stiff peaks form. When the sugar is at the hard ball stage, immediately remove it from heat. Begin whisking the egg whites again on medium speed while slowly streaming in the hot syrup mixture, be very careful as you do this. When all the syrup is combined, increase the speed to high and continue to beat for 5-6 minutes until the mixture is very glossy and holds stiff peaks. Stir in the chopped pistachios. Using two spoons drop dollops of the mixture on the wax paper, using the second spoon to help push it each piece off. Each one will be unique but try to keep them similar in size, no larger than a golf ball. Let the candy set for at least 1 hour or until it no longer feels tacky to the touch. Store in an airtight container at room temperature.