Green, fresh walnuts turn a dark mahogany brown and are preserved in syrup, with a delicious, rich, nutty texture.
What do you need to make walnut jam?
1-2 pounds of fresh, green walnuts (about 23-30 depending on size)
1-2 pounds of sugar
1-4 cups of water
1-2 tablespoons of lemon juice
1 teaspoon of cinnamon
1 teaspoon of vanilla extract (or 1/2 vanilla bean)
4 cloves (or 1 teaspoon) of cardamom
How to make walnut jam from scratch?
1. Find Fresh Walnuts
This will probably be the hardest part of the process. If you are lucky enough to have your own black walnut tree or use one, then pick them when they are green in June, as early as possible. The size of a green nut should be between that of a very large olive and that of a very small egg. If you harvest before the hard inner shell has developed, each one should be very easy to cut in half and should be light green and white inside.
2
Shell and Soak Your Green Walnuts
You’ll need gloves for the next step: rubber kitchen gloves are fine, although latex gloves will give you more comfort and convenience. Green walnuts will quickly turn a dark, coffee-colored brown when cut, staining your fingers in a way that requires weeks of relentless scrubbing.
Place the shelled walnuts in a bowl of cold water. You may want to pierce the walnuts at least halfway through with a fork, although you can do this a few days after your walnuts have soaked for a while.
Make sure you drain your shelled walnuts at this stage. This will be important in a later step.
Soak your walnuts in fresh, cold water for 9 days, changing them twice a day. They will float, but you can keep them in the water by placing a ceramic plate on top. They will turn from golden to green by the time you rinse them. Rinsing is important because you’re basically washing away the natural bitter taste in unripe walnuts. You will also notice that the walnuts will slowly darken, from light green to dark green to finally a dark mahogany brown.
If you want a firmer walnut preserve, transfer and soak them in lime water (slaked lime dissolved in cold water) for 5-8 days, changing the water daily. Lime contains calcium hydroxide, which is safe in small amounts and precipitates the pectin naturally occurring in the walnut, resulting in a firmer (but still soft) preserve.
You will still want to soak them in plain cold water for the 9th day.
3
Make the syrup and cook your walnuts
Prick each walnut 3-4 times with a skewer, a large knitting needle or a fork, then drop it into boiling water for 10 minutes. Wait until it dries completely.
Add the sugar and water to a saucepan. Bring to a boil and then add the walnuts. Bring back to a boil and cook the walnuts in the syrup for about 30 minutes. Cover the saucepan and leave to cool for about 6 hours (ideally overnight).
Add the lemon juice, cinnamon, vanilla and cloves/cardamom to the saucepan, return to the heat and cook for a further 30 minutes. Check the walnuts to make sure they are soft, if they are still too firm, cook longer until they are soft.
When the walnuts are ready, pour them and the syrup into sterilised jars and seal tightly. It is advisable to wait at least a week before consuming. But they should be stored in a dark and cool place for at least 6 months.
