Cut any large potatoes in half but otherwise leave them whole. Put the potatoes into a large pan of boiling water with a teaspoon of sea salt and simmer for around 20 minutes until tender.
Put the butter in a bowl large enough to fit on top of the pan of potatoes and leave it there to melt slightly.
Make the salsa verde by putting all the ingredients in a food processor or mortar and pestle and crush to an almost smooth paste. Taste and add more honey, vinegar or salt as needed.
Add the softened butter to the salsa verde and mix before scraping onto a piece of parchment, squishing into a log, wrapping and scrunching the ends closed like a Christmas cracker.
When the potatoes are tender, drain, return to the pan and add a couple of tablespoons of the salsa verde butter. Toss until it is melted, coating the potatoes then serve.