Sweet and sour, this curd is perfect as a tart filling. Before using the curd, whisk it well, so it is easier to pour. You can substitute any other citrus juice for the limes, if you prefer.
Prepare a bain marie or double boiler: Place a small pot filled with a little bit of water over medium-low heat and place a heat-proof bowl on top of the pot (make sure the bottom of the bowl isn’t touching the water). Add the lime juice, powdered sugar and eggs into the bowl. Whisk the mixture well, non-stop, until the mixture thickens.
As soon as the mixture thickens, remove the bowl from the heat. Pour the mixture through a fine mesh sieve and into another bowl and add the butter. Whisk the mixture well until the butter is melted and is emulsified into the mixture (if needed, use a hand blender).
Place plastic wrap directly on top of the surface of the curd (to avoid any film from forming) and refrigerator until completely cooled. Once cooled, whisk the curd again and transfer to a sterilized jar. The curd can be stored in the refrigerator for up to 3 weeks
