Put the shallot, white wine and white wine vinegar into a small frying pan and reduce to 3 tbsp. Meanwhile, blanch the samphire in boiling salted water for 1 minute, then drain.
Whisk the cubed butter into the wine reduction over a low heat, one piece at a time, only adding another once the previous one is fully emulsified. Once all the butter is in the sauce, add the samphire and chives, season, heat through and serve.
