Sterilize your mason jar(s) by boiling them in water and ensuring they are completely dry. Set aside. (Use a jar large enough to hold roughly two cups of jam.)

Remove the tops from the strawberries and dice them up. (Refer to the note about blending.)

In a large pot or deep saucepan, combine the washed strawberries, granulated sugar, and freshly squeezed lemon juice.

Stir well to coat the strawberries in sugar.

Allow the strawberries to sit for about 10-15 minutes until they start to release their juices.

Turn the heat to medium-low and stir with a rubber spatula until the sugar has completely melted. Be sure to scrape any sugar off the sides of the pot and spatula. (All the sugar must dissolve to prevent the finished jam from crystallizing.)

Simmer for 10-15 minutes, stirring frequently and mashing the strawberries with a potato masher as they soften.

Bring the mixture to a full rolling boil, and continue boiling until the mixture reaches 220°F. Stir constantly to prevent the mixture from burning.

Remove from heat. (Optional: Skim off any foam from the top of the jam.)

Pour the jam into the prepared jar, leaving about 1/4 inch of space at the top.

Immediately place the lid on the jar and allow the jam to cool to room temperature.

Refrigerate until firm, and store in the fridge for up to two weeks.