Ingredients
Method
- Put the frozen berries in a thick-bottomed pot. I prefer a good copper one, or enameled cast iron like Staub or Le Creuset, for making jam.

- Pour most of the sugar over the berries, setting aside 1 tablespoon for later. Split the vanilla bean in half and scrape out the seeds. Rub the seeds into the reserved sugar with the flat of a knife until they're evenly mixed in. Sprinkle the vanilla sugar over the berries and drop in the bean.

- Add the lemon juice.

- "Stir the sugar into the berries with a wooden spoon, then cook over low heat for 5 minutes until the berries have released their juice."

- Then turn the heat up to high. Keep a close eye on it from here on — it can burn fast.

- After about 15–20 minutes, the jam will start to thicken. It's done when you can run a spoon through it and see a clear path to the bottom of the pot. The liquid no longer flows back together — the pectin has set, and it's ready to pour into sterilized jars.

- Once the jam is ready, let it cool, then share it with someone you care about.

Notes
You can always double or triple the recipe, though that will add quite a bit to the cooking time. I often make 2 kg at a time — that way, you save on electricity and have plenty of summery sweetness in the fridge for when you're craving it.
