Add the fresh blueberries and sage leaves to a cocktail shaker.
Muddle firmly until the blueberries are fully broken down and the sage has released its oils.
Add the vodka, Martini Bianco, blueberry syrup, lemon juice, and a generous handful of ice.
Shake hard for about 15 seconds until well chilled.
Double strain into the chilled martini glass.
Garnish with a few fresh blueberries and a small sage leaf.
Notes
Blueberry Syrup:To make the blueberry syrup: combine 1½ cups blueberries, 1 cup sugar, 1 cup water, and 1 tsp lemon juice in a saucepan. Simmer 10 minutes, strain well, and cool completely. Full recipe at blueberry simple syrup.Muddle the blueberries firmly - they need a proper press to break down. Stop once they're broken down so the sage doesn't get over-worked.Double strain through a fine mesh sieve to catch blueberry skins and sage bits for a clean drink.Martini Bianco is sweeter and more floral than dry vermouth. Either works but Bianco is the better match for the blueberry and sage.For a more sage-forward drink, swap the blueberry syrup for sage simple syrup.