1. In a saucepan, combine the raspberries and sugar. Let stand for 1–2 hours to allow the raspberries to release their juice.
2.  Add vinegar and salt. Bring to a boil, reduce heat and continue cooking for 30 minutes, stirring occasionally. Heat over low heat, stirring occasionally until mixture simmers. Skim while cooking. Do the plate test to make sure the jam is ready.
3. Pour jam into jars. Mix with a wooden spoon to remove air bubbles. Clean jar rims. Close jars without over-tightening the rings.
4. Place jars in a pot of hot water. Carry out a heat treatment for 10 minutes, turn off heat and let jars sit in water for 5 minutes before removing.

Chef’s secret 

• Plate test to check consistency: Before starting the recipe, put a plate in the freezer. When it’s time to check the consistency, spoon 5 mL (1 tsp.) of jam onto the plate. The jam is ready if it is thick and slowly slides on the plate when tilted. If not ready, put the plate back in the freezer, continue cooking and repeat test.

The acidity of the brine lets you use the boiling water technique to can the blueberries. 

• Sterilize the jars by immersing them in boiling water for about 5 minutes. The flat lids should be new to ensure a proper seal. They should be soaked in hot water before use.
• Fill the jars, leaving a 1 cm (½ in.) space at the top.
• Close the jars with their lids and rings without overtightening.
• Immerse the jars in a pot of water, ensuring they are at least 2.5 cm (1 in.) under the surface. Cover and bring to a boil over high heat. Let boil according to the recipe instructions.
• Remove jars from water and let stand for 24 hours. The lids should be depressed and make a small popping noise: this means the jars are properly sealed.
• The jars can be stored for one year in a dark, dry, cool place.