Lemon curd is a wonderfully sweet and tangy, velvety smooth dessert spread. It has a rich and creamy texture, and goes beautifully served on scones, muffins, cakes or as a filling in tarts or pies. This same recipe can be modified to make lime curd, orange curd or passion fruit curd by substituting the lemons with either limes, oranges or passion fruit.
First, zest the lemon, taking care to ONLY zest the outer yellow peel of the lemon and not the white inner pith which tends to be very bitter.
Put the butter, sugar, icing sugar, salt and zest in a bowl, beat with a mixer until smooth and creamy. Add the eggs one at a time, beating well after each addition. Then add the lemon juice and mix it in. Place a pan of water on the heat and bring the water to a boil. Then place the bowl containing the beaten curd mixture over the boiling water and cook this double boiler for about 10-15 minutes whisking constantly until the curd thickens.
If you want the curd to look bright, you could add a few drops of food colouring to intensify the colour. The curd will thicken further as it cools, however if you want an especially thick curd for use in a pie or pastries, then mix half a tsp of cornflour in a few drops of water and then add it into the curd mixture and continue whisking over the double boiler until it thickens.
Take it off the heat and continue whisking for a couple more minutes. Then transfer the curd into a bowl and place a piece of cling film/plastic wrap over it so that it directly touches the surface of the curd. This will prevent a skin from forming over the curd. Let it cool to room temperature, then refrigerate until needed. You will notice that the flavour continues to develop and mellow as it cools, and the texture will become thicker.
The curd can be stored for up to 2 weeks.