Combine ½ cup (100 g) of granulated sugar, ½ cup (120 ml) of water, and 1 tablespoon of dried edible lavender flowers in a small saucepan over medium-low heat. Stir occasionally as the mixture warms, and cook for 3–5 minutes until the sugar has dissolved completely and the liquid is just beginning to show the faintest color from the lavender. Remove from heat — do not simmer aggressively or boil, which pushes the lavender's volatile aromatic oils out of the syrup before the steeping period even begins. Allow the syrup to steep undisturbed for 2–3 hours at room temperature. This extended steeping period at ambient temperature extracts the clean, floral top notes of the lavender without the bitterness that continued heat would introduce. Taste at the 2-hour mark — the syrup should smell and taste clearly floral, soft, and aromatic. If a stronger lavender presence is wanted, steep for up to 4 hours, but no longer. Strain out the lavender flowers completely through a fine-mesh sieve and set the syrup aside. It should be pale amber with a soft purple tint and smell unmistakably of lavender without any soapy or medicinal edge.

Add 1 cup (150 g) of fresh blueberries and the full ¾ cup (180 ml) of freshly squeezed lemon juice to a large pitcher or cocktail shaker. Muddle firmly and thoroughly until every berry has burst and released its juice — the mixture should turn a deep, vivid purple and the lemon juice should be visibly colored throughout. Unlike the gentle herb muddling used elsewhere in this collection, blueberries benefit from more assertive pressure because the goal is maximum juice and color extraction rather than a delicate aromatic release. Work the mixture for a full 60–90 seconds to ensure complete breakdown. If a cleaner, clearer finished lemonade is preferred, strain the muddled blueberry mixture through a fine-mesh sieve at this point, pressing firmly to extract all usable juice before discarding the solids. If a more rustic, textured result is acceptable, proceed without straining.

Add ½ cup (120 ml) of the cooled lavender syrup to the blueberry-lemon mixture and stir to combine. Pour in 4 cups (950 ml) of cold water and stir again until fully integrated. Taste the base at this point before adding ice or soda — it should taste tart, fruity, and clearly floral, with the lavender present as a soft background note rather than a dominant flavor. If it tastes flat, add an additional squeeze of lemon juice. If the lavender is too subtle, add a small additional splash of lavender syrup — no more than a tablespoon at a time. Add 4 cups of ice directly to the pitcher, then pour in 3–4 cups (700–950 ml) of ice-cold club soda slowly down the side of the pitcher to preserve carbonation. Stir once or twice minimally and serve immediately.

Pour into ice-filled glasses, ensuring the muddled blueberry pieces and ice distribute evenly if the mixture was not strained. Garnish each glass with a few of the reserved fresh blueberries, a lemon wheel, and a small fresh lavender sprig. Serve immediately — carbonation begins dissipating the moment the soda is added, and this drink is at its most alive in the first 10–15 minutes after assembly.