Heat the water to 90–95°C (195–203°F). Add the black tea bags and steep for 2½–3 minutes maximum. Remove the tea bags without squeezing and let the tea cool to lukewarm.
Add the lavender buds to the warm tea. Let infuse for 4–6 minutes only, just until a soft floral aroma develops. Remove immediately — overinfusion turns this drink soapy.
In a small saucepan, combine the blueberries, sugar, and water. Bring to a gentle simmer over medium-low heat and cook for 8–10 minutes, just until the berries burst and release color. Do not reduce or thicken. Remove from heat.
Strain through a fine-mesh sieve into a bowl or measuring jug. Do not press the pulp. Discard solids and let the syrup cool completely.
Stir 120–160 ml of the cooled blueberry syrup into the lavender-infused tea. Taste and adjust cautiously — blueberry should support the tea, not dominate it.
Refrigerate for 1–2 hours until fully cold and integrated.
Fill glasses with ice, pour over the chilled lavender blueberry iced tea, and garnish with fresh blueberries and a lavender sprig.
