Pickling spice is a blend of spices that is used in conjunction with vinegar or brine to preserve foodstuffs. You can pickle many things - from gherkins or fruits, to eggs or onions. The food naturally ferments in the pickle, taking on the familiar "pickled" flavour. Pickled food will last for many months.
Grind the pickling spice in a blender or mortar and pestle and mix with enough vinegar or brine (salted water) to cover the food to be pickled. Wash jars out thoroughly using boiling water and cover with the pickle mixture. Seal the jars tightly and leave for as long as desired to bring out the flavour.