Wash 2 cups of blueberries under cold water and place in a medium-sized pot. Add 1 cup of water.

Gently mash the blueberries with a potato masher for about 5 minutes.

Bring the mixture to a rolling boil, then reduce the heat and let simmer for 15 minutes.

Remove from heat and strain the mixture through a fine sieve or food mill.

Return the liquid to the pot, add the zest of 1 lemon, and your desired sweetener. Simmer for an additional 10 minutes.

Squeeze in the lemon juice and bring to a light boil for 2 minutes.

If canning, pour the hot syrup into sterilized jars and process in boiling water for 10 minutes.

Store the syrup in an airtight container or freeze for later use.