juniper berries
Dried blue-black berry cones of the juniper shrub, resinous and spicy with a hint of pine and citrus.
In German-speaking countries juniper berries sit in the spice aisle of almost every supermarket; in English-speaking countries look in larger supermarkets, delicatessens, spice shops or online. Crush them lightly before use so they release their aroma.
Substitute:
There is no true substitute; a splash of gin carries the juniper note into sauces and marinades, while a little rosemary with bay leaf only catches the resinous side, not the fruity sweetness.