Because I believe citrus curd should be tart and zesty, not rich and creamy.
And because I’m pro–crystallised ginger.

Based on Low-Fat Lemon Curd by Baking Bites.

Gather:
2/3 cup lime juice (6 or 7 large limes)
Zest from those limes
4 pieces crystallised ginger*
2 eggs
10 tbsp icing mixture**
2 tsp cornflour

Then:

1. Using a microplane, zest the limes into a small saucepan.
2. Finely mince the crystallised ginger (if you’re using it) and add it to the saucepan.
3. Juice the limes until you have 2/3 cup, add the juice to the saucepan and set it aside on the stove.
4. In a medium bowl, whisk the eggs and set aside.
5. Place the saucepan over a medium heat, add the icing mixture and whisk constantly until the sugar has dissolved and the surface is steaming.
6. Very, very slowly pour the hot lime/ginger/sugar mixture into the eggs — only about a tablespoon at a time, so you don’t instantly cook the eggs — whisking as you go.
7. When it’s all combined in the bowl, transfer back into the saucepan, add the cornflour, and continue to heat/whisk until the mixture thickens. You know it’s ready if a little bit ‘gels’ when you drop it on a cold saucer.
8. Remove from from the heat and immediately transfer to a clean jar/container. The curd will thicken rapidly as it cools, so don’t worry if it’s still a little bit fluid.

Notes:
Needless to say, you can use lemons and/or grapefruit instead of limes (I have). Oranges might be a bit too sweet unless you’re using seville oranges or underripe navels.
This makes a medium jam jar of curd (or enough to fill a shallow tart***) and I’ve kept it in the fridge for around a fortnight. But you can very easily halve all the ingredients if you only want enough to have it on toast for a few days.

*Omit this if you hate crystallised ginger. (Apparently lots of people do? Crazy.)
**Icing mixture, not icing sugar — the extra cornflour will help the curd set in the absence of butter.
***Which is how I justify categorising this recipe as ‘baking’.