Wash your oranges. Slice off the ends and throw them away. Then slice your blood oranges as thinly as you can and remove any seeds you see. In a large jar or bowl place your sliced blood oranges and toss them together with 1 teaspoon of salt and 2 cups of granulated sugar. Cover and Let the mixture sit for at least 24 hours. Give the mixture a good stir or shake every few hours.
Tip your orange mixture into a large bowl. Remove the sliced oranges and set them aside for later. Left in the bowl you should have sugar syrup that has formed from the sugar and blood orange juice. Add 4 large eggs to the mixture and whip them together for 5 minutes until the mixture is light and frothy. Make your short bread crust.
Shortbread Crust:
Beat together butter and sugar until pale and fluffy, about 4-5 minutes. Then add in vanilla extract, salt, and flour until mixture is crumbly.
Preheat oven to 350 degrees. Press dough into a tart pan or pie dish (I used a 10” tart pan), really pushing it into the sides and grooves of the tart pan making a nice crust.
Freeze your crust for 20 minutes then bake crust for 10 minutes. Let cool and then continue on to assembling your tart.
Making the Blood Orange Curd & Assembling the Tart:
Take your cooled shortbread crust and layer your sliced blood orange slices into it. Make sure you remove any slices that are too thick.
Pour your blood orange curd (your sugar/egg mixture) over top of the blood orange slices. You’ll notice that your curd will have lots of air bubbles over the top. Take a spoon and scoop away the air bubbles. If you skip this part they will form a crust over top of the blood oranges and you will not see the blood oranges through from the top, however, if you leave it it will not effect the flavor.
Bake your tart at 350 degrees Fahrenheit for 50-55 minutes until your curd has a slight wobble but is set. Be sure to check on your tart every 15 minutes, if you see any bubbles or a skin forming over top of your blood orange slices, take a spoon and scoop it away so that you really see those beautiful blood oranges. Cool completely before serving.