Step 1

Harvest unripe black walnuts directly from the tree. While it may be tempting to harvest walnuts that have already fallen, you will want to cut some of them in half to make sure they're pearly white and clean on the inside, without any spotting or deterioration. If you harvest walnuts from the ground, wash them.

Step 2

Wearing gloves, cut the walnuts in half using a heavy knife, preferably on a cutting board you don't mind getting stained. Older recipes often mention crushing or pounding the unripe nuts, which you could also do, but beware of splattering juice.

Step 3

Mix the walnut with the sugar, then pack into a container that can accomodate the entire mixture. For the amount listed, you would want a half gallon mason jar.

Step 4

Allow the walnut-sugar mixture to sit at room temperature or outside for at least 30 days, and up to a few months, opening the jar occasionally to release carbon dioxide as the mixture will ferment. Shake or stir it occasionally to help it on it's way, which will coat the nuts in the fermenting syrup and help prevent mold.

Step 5

After at least 30 days, scrape the sugary walnut sludge into a non-reactive sauce pot with high sides, bring the mixture to a full boil, then strain out the walnuts using a slotted spoon. Discard the walnuts and thank them for their service.

Step 6

As the syrup cooks, it will begin to foam-a byproduct of the fermentation process. You can resist the urge to skim off the foam as it will subside and disappear as the syrup cools.

Step 7

With clean mason jars at the ready, bring the syrup back to a brisk simmer, turn off the heat and wait a minute or two for the foam to settle. Pour the piping hot syrup into the jars leaving 1/2 inch or so of headspace (the amount headspace is more to prevent sticky leaks than for safety as the syrup is very stable), screw on the lids tightly, then turn the jars upside down and allow to cool and seal. The syrup will last for years.