Creating curd!
When cooking a curd, you need to be mindful of the heat! Overheating a curd can cause the eggs to scramble, leaving you with sweet lumps of egg in your lovely fruity creation! This recipe is at particular risk of this, since we are only making a very small batch of curd, making it prone to boiling over unless you are working at very low temperatures.
Hopefully, if you keep the hob at the lowest heat possible and stir the contents of the pan constantly, you should be able to produce a nice, smooth result! If you are particularly concerned, however, you can cook the curd in a heatproof bowl set over a pan of boiling water, which provides you with a less direct heat. This will take quite a bit longer to cook (hence why I don't normally do this, being an impatient wotsit!), but if you are struggling to achieve a smooth curd, this could be the solution for you!
Another top tip is that, should your curd start to boil and bubble before you've popped the egg in, remove the mixture from the heat and allow it to cool for 5 minutes before you add your beaten egg. This will reduce the chances of the egg scrambling as it hits the pan and prevent your curd from going grainy.