Preheat your oven to 350°F (175°C).

In a large mixing bowl, combine flour, sugar, and salt. Cut in the cold butter until the mixture resembles coarse breadcrumbs. Press into the bottom of the baking dish.

Bake the crust in the preheated oven for about 20 minutes or until lightly golden.

For the filling, combine lemon juice, rhubarb, and eggs in a bowl. Blend until smooth with an immersion blender.

Stir in lemon zest, sugar, and flour until just combined. Fold in remaining rhubarb and vanilla extract.

Pour the filling over the pre-baked crust and bake for about 35 minutes.

Allow to cool completely in the pan for 1 hour, then refrigerate for at least 2 hours before slicing.