Place the thyme sprig in the palm of your hand and slap it to release its oils.
Twist it and place in the bottom of a 10-ounce highball or Old Fashioned glass.
Fill with ice and set aside.
In a shaker, muddle the blueberries and lemon. (If blueberries are out of season, use 2 teaspoons of high-quality blueberry preserves instead.
You'll have to adjust the amount of agave nectar depending on the sweetness of the preserves.) Add the vodka and agave nectar, and fill with ice.
Shake vigorously for 10 to 20 seconds and strain into the prepared glass.
Take a nice large, pretty sprig of thyme and slap it before using to garnish the drink.