Pour the blood orange juice into a small saucepan and set over medium-high heat. Cook until slightly reduced by half, about 3 to 5 minutes. Set aside and let cool slightly.

Beat together the softened butter with the sugar, in a glass or metal bowl (your stand mixer bowl will be perfect here) until lightly and fluffy. Add the egg yolks and stir until well combined. Add the whole eggs and beat until well incorporated. Stir in the salt, lemon juice and slowly mix in the blood orange juice. The mixture will appear to be curdled, but that's okay.

Fill a medium saucepan with a bit of water and bring to a simmer. Place the bowl over the pot of simmering water (making sure that the bottom of the bowl doesn't touch the water) and cook, stirring often, until the sugar dissolves and everything comes together in a smooth texture. Remove the curd from the heat once it thickens and a thermometer reaches 166 degrees F. It'll continue to thicken as it cools.

Run the curd through a fine mesh sieve to remove any bits and to ensure it's smooth. Transfer to a jar with a lid or a container and store in the fridge for up to a week. Enjoy!