Grate the zest from 4 oranges and place in a heavy-based saucepan. Squeeze the juice and set aside.
Add 4 large eggs to the pan and whisk until the eggs are well broken up and mixed with the peel. Whisk in 350g (12oz) sugar and orange juice.
Add 225g (8oz) butter to the pan. Squeeze the juice from 1 lemon, add 1 tablespoon cornflour and mix to a smooth paste then whisk into the pan.
Place the pan over a low heat and cook gently whisking continuously until the butter melts and the mixture thickens. About 10-12 minutes.
Remove from the heat and pour into warm sterilised jars. Cover with a waxed disc and seal while hot.
Video
Notes
Cook's tips
I cannot stress how important it is to cook the curd over a low heat and make sure if you are cooking with gas that the flame does not come up the side of the pan.
You can reduce the butter by up to ⅓ for a slightly less rich curd.
I like flecks of zest in my curd and it adds more flavour. For best results use a fine grater to remove the zest. I recommend a microplane zester.
I used golden caster sugar to make mine (because generally, I prefer to use unrefined sugar in my cooking and that is what I had to hand) but you will get a brighter colour if you use white caster.