Blend blueberries, ginger, honey, water, and lemon (if using) in a high-powered blender, on high, for 30 seconds. Strain the mixture through a fine-mesh strainer into a glass jar or measuring cup, using a spoon to push the juice through the strainer until only pulp remains. Taste and adjust any sweetener here. Discard the pulp.
Add about 1/4 cup of blueberry juice to the bottom of a low glass with ice. Top off with the sparkling water or ginger ale. Add ginger slices for garnish, if desired.
Notes
Lemon is great for a vitamin C boost for those not on HYH or following a low histamine diet. It's delicious! This recipe is also great without it or you could add another tart juice like pomegranate.
Non-alcoholic ginger beer that make great mixers are Fever Tree or Regatta.
Frozen wild blueberries can be found with other frozen fruit. A great deal at Costco or Trader Joes. Regular frozen blueberries can be substituted if not available