Beat the butter and sugar together until light and creamy. Add in the flour and salt and mix until just combined. the mixture should clump together when you squeeze it together.
Press the crust into the bottom and sides of the tart pan. Bake for 13 - 15 minutes or until a light golden brown. Set aside.
For the Curd
In a saucepan heat the blood orange, vanilla, and raspberries on medium. muddle the raspberries to help release their juices. Heat until lightly boiling.
In a bowl, whisk the eggs and sugar together until light and ribbony. slowly add one third of the blood orange mixture into the eggs, whisking constantly. Add another third of the juice while continuously mixing. Slowly add the egg mixture back to the saucepan and whisk constantly, until the curd begins to thicken. Thr best way to test this is by running a finger down the back of your spoon and check for a line to remain on the spoon. once it reaches this point, turn off the heat.
Bloom the gelatin with a tablespoon of water and pour into the curd and mix well.
Strain the curd through a fine mesh strainer. and allow to cool completely. Once the curd is cooled, pour into the prepared tart pan.
For the Raspberry Meringue
In a small saucepan, heat the raspberries and the sugar together on medium. Break of the raspberries once the begin to release their juices. Bring to a high simmer for about two minutes, or until the raspberries have completely broken down and the juices have thickened. Strain the seeds from the syrup and set aside the syrup. Discard the seeds.
Beat the egg whites until sock peaks form. Add the cream of tartar and continue to beat. Slowly add the raspberry syrup to the egg whites, then beat the whites on medium-high until it forms stiff, glossy peaks.
Fit a piping bag with a large star tip and pipe the meringue onto the tart. Toast the meringue with a kitchen torch.
Notes
Store in an airtight container for up to four days.