(or glasswort, or pickleweed as it's also known) grows in tidal zones and muddy sand flats around estuaries and tidal creeks. It's a succulent plant of the salicornia species and you can eat young samphire raw. As a vegetable, it's delicious and unique.
Many years ago (in my youth) we used to live about half a mile from The Wash (a large tidal inlet on the East coat of England). I still remember a gang of us, when the tide was low, going down onto the salt marshes on summer weekends to collect samphire. Usually these trips ended up in mud fights and (since the tide went out about 2 miles over the mud flats) we would go and swim in the local stone pits to wash.
Samphire's delicate saltiness makes it a perfect partner to fish - I particularly like it with a large fillet of halibut and a glass of Chablis.
How to make Samphire:
Start by picking through the samphire to remove roots and any obvious tough stems. Wash and rinse it thoroughly to get rid of any grit, mud or sand, and break up larger, multi-branched stems into smaller pieces. You can expect to lose anything up to a quarter of the samphire in the cleaning and trimming... unless, of course, it's early season (June in the northern hemisphere) and the samphire is particularly tender, in which case you may lose almost none.
Bring to the boil a large pan of fresh, un
salted water, drop in the samphire and cook for three to four minutes. Drain, toss with the butter and olive oil, and season with freshly ground pepper. Serve immediately with lemon wedges, alongside a good piece of grilled or poached fish.