Make your pastry in advance by mixing diced cold butter with flour in a food processor until you reach a breadcrumb texture. Add in your Black Truffle pate and then gradually add water until you have a dough consistency. Form the shortcrust pastry into a ball, cover and leave in the fridge for 1-2 hours to rest.
Sauté your shallot, garlic and mushroom with a small knob of butter until golden. Add chopped tarragon, Truffle Pate and season to taste. Mix in a bowl with potatoes and blue cheese.
Roll out your pastry into 4—6 pasty rounds and then place a handful of filling into the centre of each.
Fold over and crimp the pastry to seal in a rolling rope crimp. Glaze with beaten egg and bake in a preheated oven at 200˚C for 30 mins until golden brown. Serve with Truffle mustard or mayo