Soak the porcini in the boiling water for 20 minutes until soft and rehydrated.
Toast the walnuts in a dry frying pan until just beginning to brown and they give off a lovely toasted smell.
Fry the shallot very gently in the olive oil until soft, add the chestnut mushrooms and fry for 5 minutes or until they have released their juices.
Add the porcini and garlic and fry for a minute before adding the porcini soaking liquid, tamari/soy and the sherry.
Turn the heat up to high and cook off the liquid until only about a teaspoonful remains.
Transfer the mushroom mixture to a food processor. Add the walnut pieces, chopped thyme and a good grinding of black pepper.
Whizz together, stopping to scrape down the sides, until you get a smooth pâté. I like to keep a bit of texture so I pulse until I'm happy with it!
Taste and add salt and more pepper if needed.
Transfer to a serving dish and chill for an hour or two.
Top with extra walnuts and pink peppercorns and serve.