In the pot, add the sugar and the cornstarch. Gradually add the milk while whisking.Add a pinch of tumeric for the colour and 1 tsp of vanilla extract.If you wish to make Lemon Curd, also add the zest of 1 lemon. If you want to make simple custard or pastry cream, just skip to the next step.
Cook at medium heat until the cream thickens, continuinig to whisk to avoid the formation of lumps.
Now leave the custard to cool down covered with some cling film in contact with the surface of the custard.
Storage In the fridge: 3-4 days in Tupperware. When needed, you can blend it with a hand blender to make it creamy again.