Add the strawberries and sugar to a large stockpot and cook over medium-low heat until the berries dissolve. Stir in the lemon.
Once the mixture thickens and reaches 220°F, stir the pectin into the strawberries. Allow the pectin to boil for one minute without stirring and remove from the heat. Add a pinch of salt and stir.
Ladle the strawberry jam evenly into sterilized jars, leaving 1/2 inch headroom. Wipe rims. Place sterilized lids on and allow the jam to come to room temperature.
You can store jam in the refrigerator for up to 1 month or in the freezer for 6 months to a year. Or proceed to the water bath canning method to preserve it for 18 months. See canning links in notes.