Place a small plate in the freezer before you start cooking.

To a 1-quart or larger saucepan (the larger the surface area, the less time you'll need to cook them!), add the strawberries, sugar and lemon juice.

Use a potato masher or the bottom of a flat glass to lightly smash just a few of the strawberries. Smashing a few is enough to get some juices out to get things moving along.

Bring to a boil over medium-high heat while stirring frequently. Turn the heat to the lowest you can to keep it at a full boil. Let boil for about 9 minutes, turning the heat down, if needed, towards the end to prevent the strawberries from burning, until it reaches a temperature of 220 °F (104 °C). It’ll still be a bit runny but will thicken as it cools and more as it’s chilled.

When you think the preserves are ready, drop a small spoonful onto the cold plate and let it sit for a minute. Push it with your finger - if it wrinkles and holds its shape, the jam is done.

When it’s done, stir in the vanilla extract.

Remove the saucepan to a wire rack to cool completely, about 1-2 hours.

Transfer into clean jars and refrigerate for up to 1 week. Many sources say 2-3 weeks, but I like to play it safe and freeze whatever I haven't eaten after 1 week. It also freezes great and can be frozen for up to 1 year.