1 lemon, zested and juiced.
85g Caster sugar.
2 large eggs.
Bring the water in the pan to simmering.
Place the lemon zest and sugar in a heatproof bowl.
Whisk the lemon juice and eggs together in a separate bowl.
Add the juice and egg mix and the butter to the heatproof bowl.
Place this bowl over the pan and continue stirring until the curd thickens at about 80C.
Remove from the heat and pot into sterilised jars before lidding and storing in the fridge.
This made about 340g (12oz) curd.
Three steps to success: a heatproof bowl that fits securely over a pan so that the water won’t touch the bottom of the bowl and the curd heats in the steam of the simmering water; a hand-whisk; a talking thermometer.
It is quicker to make if all the ingredients are at room temperature.
Wash out the jars and put in the oven on the lowest setting to sterilise and dry.
Store the curd in the fridge where it will last for a week or so depending on your level of greed.
Alternative versions could be orange (especially Seville), lemon, lime or even grapefruit. I’ve also heard of passionfruit and salted caramel (the latter seems OTT in calories!).