Instructions: Scrub, pit, and cut the strawberries in half. Put the strawberries and sugar in a big mixing bowl. Mix everything together. Stirring periodically, let the strawberries and sugar mixture macerate for approximately one hour. Transfer the mixture to a large pot with a heavy bottom after an hour. Stir in the butter if using, lemon zest, and lemon juice. Bring the mixture to a boil while stirring continuously over medium-high heat. After lowering the heat to medium-low, simmer the mixture for 20 to 30 minutes, stirring frequently, or until it thickens and takes on the consistency of jam. To check if the jam is ready, put a small amount on a plate that has been chilled and see if it sets. When the jam is done, take it off the heat and allow it to cool a little. Leaving a quarter of an inch of headspace, carefully pour the hot jam into sterilized jars. Put the lids on the jars firmly. Let the jars cool until they reach room temperature. You should hear the lids pop as the jam cools, signifying a good seal. After opening, place the strawberry jam in the refrigerator and store it somewhere cool and dark. It will continue for a few months. Savor your homemade strawberry jam prepared in the European style with bread, pastries, or as a delectable condiment!