Preheat the oven to 400 degrees.
In a medium mixing bowl, combine the flour, salt, sugar, baking soda, and baking powder. Stir in frozen butter.
Add 1 ¾ cup starter, lemon juice, vanilla, and black raspberries.
Work in by hand, incorporating the flour into the starter, turning as you go. Add more starter if necessary. The dough will be moist due to the berries warming up and breaking apart.
Once fully incorporated, cut dough into four equal pieces.
Form each piece into a one inch thick disc on a parchment lined baking sheet and cut into 6-8 pizza slices using a dough scraper or turner.
Bake at 400 degrees for 15-18 minutes, until the scones are firm to the touch.
Remove and allow to cool.
Combine about ¾ cup powdered sugar and 2 tablespoons lemon juice in a liquid measuring cup. Whisk until smooth. Give it a taste test and see if you need more lemon. If you like a thicker glaze, use ¼ teaspoon extract and then 1 tablespoon lemon juice. Drizzle over cooled scones.