Vegan Mushroom and Walnut Pâté en Croûte

Soak the dried porcini in the boiling water and leave for 30 minutes. Once softened, squeeze the mushrooms dry over the bowl, keeping every drop of liquid, then finely chop the porcini and set aside. Strain the soaking liquid through a fine sieve lined with kitchen paper and reserve 200ml for the aspic.

Pulse the king oyster and chestnut mushrooms separately in a food processor until coarsely chopped, about 5mm pieces — do not purée. Transfer to a clean kitchen towel and wring out firmly to remove as much moisture as possible.

Pulse the toasted walnuts in the food processor to a coarse rubble, leaving some larger pieces for texture, and set aside.

Combine the flour and salt in a large bowl. Heat the coconut oil and 120ml water together in a small saucepan over medium heat until the oil is fully melted and the mixture just begins to simmer. Pour immediately into the flour and stir vigorously with a wooden spoon until a smooth, pliable dough forms. Knead briefly for 1 minute until cohesive, then divide into two-thirds and one-third portions and cover each with a damp cloth.

Set the dough aside, covered, for 15 minutes at room temperature — it must be workable but no longer hot when you line the tin.

Heat the olive oil in a wide skillet over medium-high heat. Add the onion and cook, stirring occasionally, until softened and lightly golden, about 8 minutes, then add the garlic and cook, stirring constantly, until fragrant, about 1 minute.

Add the wrung-out king oyster and chestnut mushrooms and cook, stirring frequently, until all moisture has evaporated and the mushrooms are deeply golden and beginning to catch on the pan, about 12 minutes.

Add the chopped porcini, then pour in the Cognac and cook, stirring, until the alcohol has evaporated, about 2 minutes.

Remove the pan from the heat and stir in the soy sauce, thyme, rosemary, allspice, white pepper, salt, nutritional yeast and agar-agar powder. Transfer to a large bowl and fold in the crushed walnuts, then taste and adjust seasoning. Leave the filling to cool completely to room temperature.

Preheat the oven to 190°C, or 170°C for a fan oven, or gas mark 5 and lightly grease a 20cm x 9cm loaf tin.

On a lightly floured surface, roll the two-thirds portion of dough into a rectangle large enough to line the base and all four sides of the tin with a 1cm overhang, pressing carefully into the corners with no air pockets. Pack the cooled filling in firmly, pressing down to eliminate gaps. Roll the remaining third of dough into a lid, lay it over the filling, and crimp the edges tightly to seal. Cut two small steam holes in the centre of the lid, about 1cm wide, and insert small foil chimneys to keep them open during baking.

Brush the entire surface generously with the plant-based milk. Bake on the middle shelf at 190°C until the pastry is deep golden brown, about 50 minutes.

Remove from the oven and let it cool in the tin for 30 minutes, then transfer to a wire rack and cool completely to room temperature — at least 2 hours. Do not slice while warm or the filling will crumble.

Once fully cooled, make the aspic: combine the strained porcini liquid, soy sauce and Cognac in a small saucepan and whisk in the agar-agar powder. Bring to a full boil over medium heat, whisking constantly, and boil for 2 minutes.

Using a small funnel or piping bag, pour the hot aspic slowly through the steam holes in the pastry lid until resistance is felt and no more liquid can be absorbed. Refrigerate uncovered for a minimum of 4 hours, or overnight, until the aspic is fully set and the pâté is firm throughout.