1 cup milk
¼ vanilla bean (about 1½ inches long) or ¼ teaspoon pure vanilla extract
a twist each of lemon and orange rind
3 large egg yolks
1/3 cup plus 1 tablespoon evaporated cane juice or sugar
1 tablespoon flour
1 tablespoon cornstarch
Combine the milk, vanilla bean, and lemon and orange twists in a copper or stainless steel saucepan. Place over high heat and bring to a boil. Remove vanilla bean and twists.
Beat the egg yolks and 1/3 cup sweetener together in a bowl until the mixture whitens, using a wire whisk or electric mixer. Stir in the flour and cornstarch, blending until smooth.
Slowly pour the hot milk into the egg yolk mixture, beating vigorously with a wire whisk. If you are using vanilla extract instead of vanilla bean, add the extract now.
Pour back into the saucepan, place over medium heat, and boil the mixture for 1 minute, stirring constantly to prevent the custard from sticking to the bottom of the pan.
Pour the pastry cream into a bowl and sprinkle with 1 tablespoon of sweetener. This prevents the formation of skin on the surface. Allow to cool. Cover and refrigerate.