Add the cut strawberries, granulated sugar, and lemon juice into a large, heavy-bottomed pot. Stir well to coat the fruit evenly.

Place the pot over medium-high heat and bring the mixture to a boil. Once boiling, reduce the heat to medium-low and let it simmer.

Stir frequently to prevent burning, and continue cooking for about 45 minutes until the jam thickens and reaches 220°F on a candy thermometer or shows a gel-like set when tested on a chilled plate.

Remove the pot from the heat. If needed, skim off any foam from the top. Carefully ladle the hot jam into sterilized jars, leaving a little space at the top.

Allow the jam to cool to room temperature before sealing and refrigerating or processing further for longer storage.