Wash and hull the strawberries, then coarsely chop them.

In a large pot, combine the strawberries, sugar, lemon juice, and lemon zest. Let the mixture sit for 30 minutes to allow the strawberries to release their juices.

Place the pot over medium heat and bring the mixture to a simmer, stirring occasionally.

If desired, add pectin to the pot and continue to cook for the time specified on the pectin package, stirring constantly.

Use a potato masher or immersion blender to crush the strawberries to your desired consistency.

Continue to simmer the jam until it thickens and reaches the gel stage. To test for doneness, place a small amount of jam on a chilled plate and tilt the plate. If the jam wrinkles and holds its shape, it’s ready.

Once the jam reaches the desired consistency, remove the pot from heat and let it cool for a few minutes.

Transfer the jam into sterilized jars, leaving a 1/4-inch headspace. Seal the jars tightly.

Process the jars in a boiling water bath for 10 minutes to ensure proper sealing and preservation.

Allow the jam to cool completely before storing it in a cool, dark place. Refrigerate after opening.