This is from the UK Guardian. I thought it would be interestng to try. According to the writeup, Seville oranges are famously bitter. Of course they'd be impossible to find in Nebraska but they say realistically any orange will work (or even other fruits like lime or lemon) but the amount of sugar may need adjusting.
Ingredients
5 Seville oranges
150g white sugar
250g cold butter, diced
3 whole eggs, beaten
Instructions
1. Finely grate the zest from the oranges, or use just half if you prefer your curd to be less bitter (NOTE: as I commented above, Seville oranges are famously bitter).
2. Now squeeze the fruit to give you about 200ml juice; do so through a sieve to make life easier, because Sevilles are full of pips, which can be slippery).
3. Put the zest and juice in a small, heavy-based saucepan and add the sugar, butter and eggs.
4. Over a very low heat, stir the mixture until it has thickened enough so that it thickly coats the back of a wooden spoon and a line drawn through it holds its shape. (Mark Diacono recommends taking it to 82C/180F, if you have a thermometer) – you’re after something with the consistency of hollandaise, and bear in mind it will set further, to a spreadable consistency, as it cools.
6. Pour into clean jars or containers (it should really be eaten within a couple of weeks) and store in the fridge – not only is it excellent on toast, but is also great with plain yoghurt, whipped cream or in the centre of sandwich cakes.