5 egg yolks
175gm caster sugar
125g butter, cut into cubes
1 cup citrus juice (eg. lemon, lime, orange, blood orange, yuzu) or 1/2 cup passionfruit pulp
Place the egg yolks and sugar in a heavy bottomed saucepan and whisk together to combine.
Place the saucepan over low-medium heat and continue whisking until smooth.
Add the butter and heat slowly until the butter melts. Do not let the mixture boil.
Add the citrus juice or passionfruit pulp to the egg yolk mixture and whisk to incorporate.
Increase the heat to medium and, without boiling, keep whisking until the curd thickens up. This will take about 10-15minutes, keeping in mind it will thicken more on cooling.
Once thickened to a consistency that it coats the back of a spoon, remove from the heat.
Allow the curd to cool and then refrigerate in sterile jars until ready to use.