Make the tart shell: 

Lightly grease a 9-inch or 9.5-inch tart pan. In a food processor, place the butter, flour, raw sugar and sea salt. Pulse for a couple of minutes, until a crumbly meal forms. Add the ice water and vanilla. Pulse again, until a dough forms. Gather into a ball. Turn the tart pastry onto a floured board. Don’t over-handle it. Roll out into a thin round circle. Carefully transfer the pastry into the prepared tart pan. Gently press it into the pan, then trim the edge. You may want to keep a little extra extending over the edge, as the tart will shrink a bit when you pre-bake it. Any trimmed, excess dough can be rolled out and you can cut out little heart shapes to place on the top for decoration. Chill the prepared tart dough in the refrigerator for 1 hour.

Preheat the oven to 400 degrees F.

Remove the chilled tart dough from the refrigerator. Place a piece of parchment paper over the tart. Add pie weights or enough dried beans to cover the bottom. This will prevent the tart shell from shrinking away from the sides of the pan. Bake at 400 degrees F. for 20 minutes. Remove from the oven and cool on a cooling rack while you make the filling. Reduce the oven temperature to 350 degrees F.

Prepare the blackberry filling: 

In a large bowl, place the blackberries. Add the raw cane sugar (reserving  2 tablespoons for the top), sea salt, flour, lemon juice, lemon zest and blackberry jam. Stir together. Place this filling into the pre-baked tart shell. Sprinkle the top with the 2 tablespoons raw cane sugar. Optional: You can add a few small pieces of plant-based butter over the top. 

Bake at 350 degrees F. for 35 minutes. Cool completely on a cooling rack. Dust with a little powdered sugar just before slicing and serving. A scoop of vanilla ice cream goes great with the blackberry tart!