Make the blueberry lavender syrup. In a small saucepan, combine 1 1/2 cups water, blueberries, sugar, and dried lavender. Bring to a gentle simmer over medium heat, stirring until the sugar dissolves.

Simmer and mash. Let the mixture simmer for 5–7 minutes, gently mashing the blueberries with a spoon to release their color and flavor. The liquid should turn a deep purple and smell lightly floral.

Strain. Remove from heat. Pour the mixture through a fine-mesh strainer into a bowl or jug, pressing on the solids to extract as much syrup as possible. Discard the solids. Set the syrup aside to cool to room temperature.

Juice the lemons. While the syrup cools, roll the lemons on the counter to loosen the juice, then cut and squeeze. Strain out seeds and extra pulp. You want 1 to 1 1/4 cups of fresh lemon juice.

Mix the lemonade base. In a large pitcher, combine the cooled blueberry lavender syrup with the lemon juice. Stir well.

Add water to taste. Add 2 to 3 cups cold water to the pitcher, tasting as you go. Adjust sweetness with a splash of honey or a little more sugar dissolved in warm water if needed. If it’s too sweet, add more lemon juice or water.

Chill. Refrigerate for at least 30 minutes to let the flavors settle and the drink chill thoroughly.

Serve. Fill glasses with ice. Pour the lemonade over the ice and garnish with lemon slices, a few blueberries, or a tiny pinch of lavender on top.

Optional sparkling version. For fizz, mix the lemonade base with chilled sparkling water just before serving. Use a 1:1 ratio for a lively sparkle or 1:2 (base to sparkling water) for something lighter.