Wear gloves as walnut color stains hands heavily. Using a needle or roulade needle, pierce each unripe green walnut 10-15 times.
Place the pierced walnuts in cold water in a cool place. Change the water daily for 14 days until the walnuts turn black.
After 14 days, place walnuts in a pot with cold water, bring to a boil over medium heat, and cook for 30 minutes. Drain, rinse under running water, and drain again.
Split the vanilla pod lengthwise and scrape out the pulp.
In a large pot, combine 1.2 liters water, 1.2 kg canning sugar, vanilla pulp and pod, 1 tablespoon whole allspice, 3 carnations, 2 mace or 1/4 teaspoon grated nutmeg, and roughly 1/2 teaspoon salt. Bring to a boil over medium heat, stirring until sugar dissolves (about 5 minutes). Cool for 10 minutes, then pour over the drained walnuts. Rest for 1 day.
On day 2, pour off and keep the syrup. Add 100 g canning sugar to the syrup, bring to a boil over medium heat, cool for 10 minutes, and pour over the walnuts. Rest for 1 day.
On day 3, repeat day 2's process: pour off and keep the syrup, add 100 g canning sugar, bring to a boil over medium heat, cool for 10 minutes, and pour over the walnuts. Rest for 1 day.
On day 4, place the walnuts and syrup together in a pot and bring to a boil over medium heat. While hot, transfer into sterilized twist-off jars, seal tightly, and store in a cool, dark place for 6 months before serving.
The Boss Kitchen editorial staff oversees content review, fact-checking, and recipe verification across the site. Published articles pass through the editorial team before going live, ensuring ingredient lists, techniques, cooking times, and nutritional claims hold up in a home kitchen. The team coordinates contributions across the site writers, handles reader corrections, and maintains consistency in measurement conventions, safety guidance, and dietary labeling. Posts under this byline typically represent team-reviewed reference material, site announcements, or editorial roundups rather than individual-author features, and they are held to the same sourcing standards as bylined recipe and product coverage.