The night before baking, in a jar with a tight-fitting lid, combine the buttermilk, 2 teaspoons of the Earl Grey tea leaves, and the vanilla bean paste or extract. Screw the lid on tightly and shake vigorously. Transfer the buttermilk to the fridge to infuse overnight until you are ready to bake. Strain the infused buttermilk through a fine-mesh sieve before using in the scones.
Preheat the oven to 375°F and line a large baking sheet with parchment paper.
Measure the white sugar into a large mixing bowl. Add one teaspoon of finely crushed Earl Grey tea leaves and the blood orange zest. Use your fingers to massage the tea and zest into the sugar until fragrant.
Add the flours, baking powder, baking soda, and salt to the bowl and whisk well to combine. Use your hands to massage the cold cubed butter into the dry mixture until the dough is a sandy texture.
Pour the infused buttermilk into the scone dough. Use your hands to knead the dough together into a ball. The dough will be slightly crumbly and require a bit of pressure to stay together.
Transfer the scone dough to a clean, lightly floured work surface. Work the dough into a rough rectangle, then use a rolling pin to roll it out until it measures roughly 10 x 6 inches and 1½ inches thick. Use a bench scraper or knife to cut the dough into 8 roughly even-sized rectangular scones.
Transfer the scones to a lined baking sheet and brush the tops with the remaining one tablespoon of buttermilk. Sprinkle turbinado sugar over the tops of the scones, then bake for 20 minutes, rotating the pan halfway through.
Transfer the scones to a cooling rack to cool for 20 minutes before serving.