Kay says: "You can substitute the plums for apricots, peeled apples or peaches, which make a very similar pulp. However, soft fruit like raspberries, redcurrants and strawberries have to be sieved to take out pips and cores and blackberry or blackcurrant curds both taste fine but tend to be an unattractive pale grey-mauve colour. These curds are not as strongly flavoured as the aggressive lemon curd sold in supermarkets, and have a higher fruit content so they might be considered to be a bit healthier. Their subtlety lends itself to imaginative ways of baking and creating desserts, and they are particularly good simply spooned over vanilla ice cream!"
400g washed fresh plums
125g caster sugar
125g unsalted butter
1 egg yolk
Start by making plum pulp. Put the plums in a saucepan and cook them gently until they soften and the skins begin to shred. Then allow them to cool a little before using a wooden spoon to push them through a colander placed over a glass bowl so that the pulp is broken up and passes through but the pits (which, in wild plums, can be so small they are more like pips) are trapped.
Add the sugar and butter to the glass bowl with the pulp and place over a pan of simmering water - I prefer to put the bowl on a trivet to avoid any chance of the curd sticking to the bottom of the bowl. Stir frequently until the butter is melted and sugar dissolved. Now whisk the eggs and yolk together and beat into the mixture.
Continue to cook, beating away, until the mixture thickens - you can test this by dipping a clean metal spoon into it and watching how it coats the back. You want it to stick rather than running straight off. If you’re in doubt, unsure of your preserving skills or easily distracted, this should take about ten minutes on a timer.
Remove from heat, and while it is cooling, give it the occasional whisk to encourage the heat to dissipate and to stop it setting too firmly. When it is completely cool, pour it into sterilised jars, cover and refrigerate. A home-made curd keeps for a couple of weeks in the fridge, but rarely lasts that long, once people know it is there!