Pastry Cream (Crema Pasticcera)

1. In a saucepan, heat the milk with half of the sugar and the vanilla bean until it starts to simmer.
2. In a large bowl, whisk together the egg yolks, remaining sugar, lemon zest, and a pinch of salt.
3. Sift in the corn starch and mix until smooth.
4. Slowly pour the hot milk into the egg mixture while whisking constantly to temper the yolks.
5. Return the entire mixture to the saucepan and cook over medium heat, stirring constantly until thickened and bubbling.
6. Remove from heat, transfer to a stainless steel container, and let it cool completely.
7. Before using, whisk or beat the pastry cream to smooth out its texture.
8. Ready to use in pastry bags for tarts, cakes, and other desserts.