Fresh green peppercorns on the vine are very pretty - they look like an elongated, miniature bunch of grapes. Bite into one, however, and you'll taste the heat, although it's not as intense as that of black peppercorn - which the green peppercorn turns into, if left to ripen. The berries of the Piper nigrum vine, green peppercorns can be used fresh, although they are often brined or dried. Fresh ones aren't easy to find: you'll probably have to visit a shop specialising in Thai ingredients. Look for "bunches" that have plump, shiny berries firmly attached to the vine.
They're delicious with seafood and other dishes that call for a gentle peppercorn heat. Frying them in a little oil brings out the fragrance and flavour: do this while they're still on the vine. Afterwards, remove the peppercorns from the stalk and add them to a dish, to disperse the flavour.
If you have dried green peppercorns, you can mix them with the black and white varieties to add a more complex flavour to dishes such as steack au poivre.