Pour one-third of the filtered water into the blender—2 cups at 1×. Add the blueberries, raw honey, apple-cider vinegar, and minced fresh ginger. Secure the lid and blend on medium speed for about 50 seconds, until the mixture is an opaque purple puree with no whole berries and the blueberry skins are tiny.

Stop the blender. Add the measured culinary lavender buds to the smooth berry base, replace the lid, and blend for about 10 seconds. The lavender should be distributed and lightly broken, with small pieces still visible before straining.

Set the fine-mesh strainer securely over the bowl with its rim or arms fully supported. Pour in the puree. Let the liquid drain, pressing gently if needed, and stop when the blueberry, ginger, and lavender solids look mostly drained.

Transfer the strained deep-purple liquid to the pitcher. Add the remaining two-thirds of the filtered water—4 cups at 1×—and stir until the color is even from top to bottom.

Cover and chill until cold. Stir before serving. The finished drink should pour smoothly, look translucent at the edge of the glass, and contain no floating lavender buds.