Hull your strawberries by removing the green tops and any white core, then slice each berry in half lengthwise.

Combine the halved strawberries with the granulated sugar in a large bowl, cover, and refrigerate for at least 8 hours or overnight to macerate.

Pour the strawberries and all accumulated juices into the large stainless steel pot and stir gently to combine.

Stir in the fresh lemon juice and add the unsalted butter, pressing it down into the fruit mixture.

Set heat to medium-high and bring the mixture to a rolling boil, stirring occasionally; once boiling, increase heat to high and stop stirring to allow rapid evaporation.

If using a candy thermometer, clip it to the side of the pot without touching the bottom and heat the preserves to 220°F (104°C).

Perform the plate test by dropping a spoonful of preserves onto a chilled plate, waiting 30 seconds, and checking for a slight wrinkle when pushed.

Remove the pot from heat as soon as the mixture reaches 220°F and passes the plate test, then skim off any foam from the surface.

Let the preserves cool in the pot for about 5 minutes, then use a ladle and canning funnel to fill sterilized jars, leaving 1/4 inch of headspace.

Seal jars with lids and bands; process in a boiling water bath for 10 minutes for shelf storage or cool completely at room temperature for refrigerator storage.