1. Rinse the berries thoroughly. Discard any berries showing the slightest sign of mold.
2. Put the remaining berries in a pot along with the water and boil for about 10 min. until the berries start to turn tender.
3. Add the sugar. If you’re using fresh vanilla, slice the bean in half, scrape out the seeds an add both to the pot). Boil for an additional 10 min. If you don’t want whole berries in your jam, you can give it a gentle whiz with a hand blender. Add lemon juice to taste.
4. Test the consistency of the jam using a spoon or plate from the freezer. Continue to cook until you have the desired consistency.
5. Pour the jam into clean, scalded jars that have been sterilized with sodium benzoate or vodka. Put the lid on immediately.
To help your jam set faster, you can add some powdered pectin, which is available in most well-stocked supermarkets. Follow the instructions on the package.