Black pepper + mushroom wellington

Bring a medium saucepan of water to the boil. Add a big pinch of salt and the pearl barley. Boil for 20 minutes until the pearl barley is cooked through but still retains some bite. Drain the pearl barley and tip into a large mixing bowl.

Heat a 28cm frying pan over a medium-low heat. Pour in about 2 tablespoons of olive oil. When the oil is hot, add the leek and a pinch of salt to the pan and fry gently, stirring occasionally for 12 minutes, until the leek is completely soft and glossy. Stir in the garlic and cook for another couple of minutes before tipping the leek and garlic into the mixing bowl with the pearl barley.

In the same frying pan (no need to rinse it out), melt the butter or dairy-free spread over a medium heat. As soon as it starts to foam, add the chopped chestnut mushrooms and a pinch of salt. Cook, stirring occasionally, until all of the water from the mushrooms has evaporated and the pieces are golden in places.

Roughly chop the porcini mushrooms (reserve the soaking liquid from the porcini) and add them to the pan with the spices and cook for another couple of minutes until fragrant. Pour in 150ml of the cider and simmer until all of the liquid has been absorbed.

Scrape the mushrooms into the bowl with the pearl barley and leek. Mix in the grated cheddar or dairy-free alternative and season generously with lots of black pepper. Check the seasoning by tasting it at this stage and add more salt if you feel it needs it, remembering that the cheese is salty and will melt as it cooks. Mix in the beaten egg or chia seeds (if using chia seeds make sure the mixture is still warm, or mix a tablespoon of hot water into the seeds before adding to the mushroom mix), cover and chill in the fridge while you get on with the rest.

Next, make the caramelised shallots for the gravy and the base of the roll. Heat about 2 tablespoons of olive oil in a medium saucepan. Add the shallots and a pinch of salt and cook over a low heat for 15 minutes until the shallots are collapsing and glossy. Stir in the brown sugar and vinegar and continue to cook for 10 minutes until the shallots are a light caramel colour. Remove two-thirds of the caramelised shallots to a bowl and set aside and continue with make the gravy with the remaining shallots in the pan.

Add the plain flour to the shallots and stir continuously for a couple of minutes to cook the flour a little. Pour the remaining cider into the pan, then pour the porcini soaking liquid into the pan through a fine sieve to catch any grit. Add the thyme, stir, bring to the boil and reduce the heat to medium-low. Simmer until the liquid is thickened and reduced by a third. Set aside to keep warm.

On a clean, lightly floured work surface, roll out the pastry to an even thickness in a 40 x 30cm rectangle. Sprinkle the cornflour over the surface (this will prevent the pastry base from becoming soggy). About 6cm from the left-hand side of the pastry rectangle, arrange the reserved caramelised shallots in a 8cm-wide line down the length, leaving 3cm clear at the top and the bottom of the pastry. Create a mound over the shallots with the chilled mushroom mixture, following the line and width of the shallots. Lift the pastry over from the right side, lifting it up and over the mushroom mixture. Grip the pastry with both hands and roll it gently to lift and tuck the pastry under the filling. Bring the sides and the edges of the pastry up and pinch and crimp to create a tight seal. Brush all over with the beaten egg and sprinkle with the nigella seeds. Lift onto a flat baking sheet or chopping board and place in the freezer to chill for 20 minutes. (You can also freeze it for cooking later at this stage.)

Heat the oven to 200°C/180°C fan/gas 6.

Remove the mushroom pastry from the freezer and place in the oven. Bake for 50 minutes until golden (or add another ten or so if you made the dish ahead of time and kept it in the freezer.) Remove from the oven and allow to stand for 15 minutes before slicing. Serve with the warm gravy.