1. Wash canning jars and lids in warm, soapy water and rinse well. Keep the sterilized jars hot until ready to use.
2. Use a food processor or potato masher to crush the fresh blueberries before cooking them.
3. In a large pot, mix the crushed blueberries, lemon juice, lemon zest, and balsamic vinegar.
4. Bring the mixture to a full rolling boil over medium-high heat. Add sugar and continue boiling, stirring well, until a full rolling boil is reached, 8 to 12 minutes.
5. Remove the mixture from the heat and separate the solids from the liquid using a sieve over a large bowl. Drain the berries and set them aside. Bring the remaining liquid back to a rolling boil.
6. Continue boiling until a temperature of 221°F is reached.
7. Add the berries back into the liquid mixture. Bring it to a boil a second time and allow it to cook for two more minutes.
8. Remove the blueberry jam from the heat and ladle the hot jam into sterilized half-pint jars, allowing ¼-inch headspace.
9. Wipe the jar rims and place the canning lids and rings on the jars, making sure they are fingertip tight.
10. Place the hot jars in the boiling-water canner and process per elevation:

Altitude (ft)

• 0 – 1,000: 5 minutes
• 1,001 – 6,000: 10 minutes
• 6,000 and up: 15 minutes

Post Processing

1. Remove the canning jars from the canner and transfer them to a rack or towel to cool for 24 hours.
2. Once completely cooled, remove the screw bands and test the seals. The middle of the lids should stay down when pressed.
3. If any jar isn’t properly sealed, place it in the refrigerator and use it within a month. Otherwise, label the sealed jars of blueberry jam with the date and use them within 12 months.