
Adapted from Tartine's recipe for currant scones. UPDATE 5/12/2023: I recently updated my method, which is highlighted in bold in the recipe below. If you prefer the old method, see the notes below the recipe. In sum I now: Grate the butter using a box grater. Use 1/4 cup more blueberries. Use the same tea towel method I use for my pie dough to bring the dough together. Cut the dough into 6 large triangles as opposed to smaller circles. As always, for best results, use a digital scale to measure. To freeze: After you place the scones on a sheet pan, transfer them to the freezer. Freeze until solid; then transfer the scones to an airtight container or bag. When you are ready to bake, there's no need to thaw them. Bake as directed below straight from the freezer. The scones shouldn't take much longer to bake from frozen, but keep an eye on them at the 20-minute mark. To make your own buttermilk: Place 1 tablespoon of vinegar or lemon juice in a liquid measuring cup. Fill cup with milk (2% or whole is best) until it reaches the 1-cup line. Let stand for five minutes. Use as directed.
Preheat the oven to 425ºF. Line a rimmed baking sheet with parchment paper.
Whisk together the flour, baking powder, baking soda, sugar, salt, and lemon zest. Grate the stick of butter using a box grater, then scatter the shreds over the dry ingredients.
Toss the butter with the dry ingredients and, using your hands, squeeze it gently to disperse it throughout the flour.
Add the buttermilk and the blueberries, and mix gently with a spatula until you don’t see any dry patches in the dough — be patient here. The dough will still be shaggy and will not be a cohesive mass but when pinched, it should hold together. If the mixture seems dry, add a tablespoon more buttermilk (or more as needed). At this point, I now do what I do when I make pie dough: turn the crumbly dough out into the center of a large tea towel, grab the sides and twist the mass into a beggar’s purse, squeezing gently to help it form a disk. Open the tea towel and gently pat the dough as needed to help it come together.
Dust your work surface with flour and turn the dough out onto it. Pat the dough into a 7-inch round circle. Brush the top with melted butter. Sprinkle with sugar. Use a bench scraper to cut the scones into 6 or 8 triangles (I prefer the larger size of the 6 scones, but they are on the large side, so do 8 if you prefer smaller scones.) Transfer the scones to the prepared sheet pan.
Bake until the tops of the scones are lightly browned, 20 to 25 minutes. Remove from the oven, let cool briefly, then serve with butter on the side.