In a bowl, combine 3 oz/90 g of the water with the cornstarch to make a slurry. Add 2 oz/60 g of the granulated sugar and the egg yolks and whisk together thoroughly.
Combine 2 oz/60 g of the granulated sugar with the remaining 4 oz/110 g water in a saucepan and bring to a boil, stirring to dissolve the sugar and creating a hot syrup.