The unripe walnuts are harvested with the shell still green. This is scratched on the side and left to lie / mature for a few days. Then the bowl can be easily removed. Wear gloves, otherwise the fingernails will turn brown, which can no longer be removed.
Now the shell of the walnuts should be paler than that of ripe, dark walnuts. Crack these open and put the nuts with the other ingredients in a container and store in the dark for 6 weeks.
Sieve, filter and bottle the finished liqueur.
The difference to liqueur made with ripe walnuts later lies in the color and taste of the liqueur.