Start with clean, sterilized jars, rings, and lids. To do this, you can submerge them in boiling water for 5 minutes and remove carefully, setting them on a clean towel to dry.

Wash strawberries and discard rotten ones.

Trim as little as possible off the top of your strawberries to remove the green leaves, leaving as much of the white part as possible, and this contains natural pectin, which will help your strawberry jam set up without additional pectin.

Slice strawberries in half.

Place strawberries and sugar in a large, heavy-bottom pan over medium-high heat.

Squeeze the juice of one whole lemon over the mixture.

Bring to a boil and stir frequently for 45 minutes to an hour. Strawberry jam's set point is 220 ℉. Smash the berries a bit while stirring frequently to help break them down.

If you like a smoother or semi-smooth jam, use an immersion blender to puree the mixture until it is completely smooth.

When the jam is set (at the gel stage), carefully ladle it into clean, prepared jars using a ladle and a jar funnel, leaving ¼” of headspace.

Clean the rim of the jar well with a clean rag or paper towel.

Top with lid and ring.

Bring the water bath to a roiling boil.

Place jars into a water bath, be sure they are covered by at least 1” of water. Allow to process for 10 minutes.

Remove carefully and let the jars sit for 24 hours, be sure each has appropriately sealed, to do this push on the center button. It should not move.