Put 45ml vinegar, 45ml sugar and 90ml water in a small pan, bring to a simmer, stirring to dissolve the sugar, then take off the heat and leave to cool. Put 90g samphire in a clean jar, pour the brine over the top, then seal and leave to infuse for 48 hours in the fridge.
Add 37ml gin, 15ml white vermouth, and 7ml samphire pickle brine to a cocktail shaker filled with a few ice cubes. Stir and strain into a chilled martini glass, and garnish with a little pickled samphire.

Serves 1.

The pickled samphire will keep for a few weeks in the fridge. Use the brine as a topping for oysters or add a tablespoon or two to a potato salad. The samphire can be used as a garnish for smoked salmon, gravadlax, or chopped and sprinkled in a potato salad.