Pour the 150 grams sugar into the center of a pot to make a mound. Drizzle the 3 tablespoons water around the border of the sugar and cover the pot with a lid.
Bring the mixture to a boil and cook until the sugar fully dissolves. This keeps the sugar from accidentally crystallizing.
Add the 580 grams strawberries and stir to combine. The sugar will solidify once but don’t panic. Once the berries start releasing juice, it will melt again.
Add the ¼ teaspoon citric acid and stir when the strawberries are immersed in their own juices.
When the mixture comes to a boil, use a spoon to skim off the foam. Keep stirring the mixture and adjust the heat if necessary to prevent it from boiling over.
The strawberry preserves are done when the strawberries become translucent, and the liquid is about the consistency of maple syrup.
Transfer the preserves to a jar or glass container with a lid and let it cool to room temperature before refrigerating. They will keep for up to 2 weeks in the fridge as long as you don’t introduce any contaminants (like bread crumbs), or you can freeze it to keep it for up to 6 months.
Notes
* The foam that forms on jams and preserves is mostly pectin, sugar, and air and is perfectly edible, but it clouds the jam, which is why we remove it.