Preheat the oven to 375°F. Lightly grease a large rimmed baking sheet.

In a measuring cup, whisk together the milk and lemon juice. Set aside to curdle.

Combine the flour, sugar, baking powder, and salt in a large mixing bowl. Add the coconut oil in small clumps and use your fingers or a pastry cutter to cut it into the flour until the texture is pebble-like.

Create a well in the center and add the curdled milk mixture, vanilla, and lemon zest. Mix with a wooden spoon until about half of the flour is incorporated. Fold in the blueberries and mix until all the ingredients are just moistened. Take care not to overmix.

Place a piece of parchment on the counter. Divide the dough into two blobs. Shape each blob into a disk, roughly 8 inches in diameter. Using a sharp knife, cut one disk in half, then cut each half into thirds, so you have 6 triangles. Transfer the triangles to the baking sheet. Repeat with the other blob.

Bake for 22 to 26 minutes, until the tops are lightly browned and firm to the touch.

While the scones are baking, sift the powdered sugar into a large bowl. Add the lemon juice, coconut oil, and vanilla. Stir vigorously until a thick, smooth, pourable icing forms. If it seems too thick, add warm water by the teaspoon until the desired texture.

When the scones are done, transfer them to a cooling rack. Allow to cool slightly, then drizzle with the glaze while still warm. Serve immediately, or allow the glaze to set for a few minutes first. For a thicker, opaque glaze, wait until the scones are fully cool before drizzling.