Muddle most of the mint leaves in a cocktail shaker. Add the blueberry juice, gin, lime juice, maple syrup, and ice and shake well for 10 seconds. Strain the contents of the shaker into an ice-filled rocks glass or Mason jar and top off with the seltzer.
Garnish with blueberries and the remaining mint leaves or lime wheel and serve.
Notes
Excerpted with permission from Clean Cocktails. By Beth Ritter Nydick, W.W Norton & Company 2017.