Mushroom Wellington

Method

1. 1
   Start by finely chopping the chestnut/baby bella mushrooms until roughly chopped. For the shiitake mushrooms, remove the stems (as the stems are often too fibrous to use) and thinly slice the caps. Tear the oyster mushrooms into thin strips.
2. 2
   Heat a wide non-stick pan over high heat and caramelise all the mushrooms in batches (no oil or salt needed). Do this in batches to prevent the pan from becoming overcrowded, which would cause the mushrooms to steam and become soggy. Once they smell nutty and look caramelised, transfer them to a mixing bowl or baking tray and season lightly with a pinch of salt. You may need to add a little olive oil towards the end of cooking if you notice the mushrooms sticking to the pan.
3. 3
   To make the mirepoix, start by finely chopping the carrots, celery and onion in a food processor. You can also do this by hand with a sharp knife.
4. 4
   Next, heat a pan with the olive oil over low heat and slowly and gently cook the mirepoix for approximately 10-15 minutes.
5. 5
   Once the moisture has cooked out, it is time to season. Mix the miso paste and tomato purée with 4 tbsp boiling water until smooth.
6. 6
   Then add the miso-tomato mixture to the mirepoix together with the garlic and fresh herbs.
7. 7
   Cook everything together over low heat for another 2-3 minutes. Then add the mirepoix mixture to the mushrooms and mix well to combine. Leave to cool slightly (~10 minutes).
8. 8
   Finally, add the wholegrain mustard. To bind, add the instant mash and cornflour. Mix well to combine and set aside to cool completely. As the miso and instant mash contain salt, I wait until this point to check and adjust the seasoning if needed.
9. 9
   For ease, assemble the Wellington on a large sheet of baking paper/or the sheet it is rolled in. This makes it easier to move.
10. 10
    Start by placing the cooled mushroom filling in the centre (lengthways) of a sheet of puff pastry. Then shape it neatly and tightly into a half roll, with 5 cm of pastry on both sides and slightly more than 2.5 cm at the front and back. The Wellington will become slightly flatter during baking, so aim for more height here.
11. 11
    Then place the second sheet of pastry directly over the mushroom filling and seal it firmly all around. If there are any air pockets, they will puff up during baking.
12. 12
    Transfer the baking paper and Wellington to a chopping board/baking tray and wrap the Wellington tightly in 2 layers of cling film, then place in the fridge to chill for at least 3 hours, or up to 2 days.
13. 13
    Preheat the oven to 190°C (fan)/210°C conventional - 375°F/410°F.
14. 14
    Transfer the baking paper and Wellington to a baking tray (if it is not already on one). Trim off the excess pastry with a sharp knife and a clean cut, leaving approximately 2 cm of pastry all around. For the corners, I prefer to use a round pizza cutter.
15. 15
    Crimp the pastry edges all around with a fork. Then make shallow scores on the surface of the pastry with a sharp knife. This can be done in any pattern you like.
16. 16
    Also make 3 small horizontal slits in the top of the pastry for ventilation. Then brush the Wellington all over with an egg wash or an alternative of your choice (listed in the notes below).
17. 17
    Place the Wellington in the preheated oven and bake for 55 minutes or until golden brown and puffed. Optionally, apply another layer of egg wash during the final 15 minutes of baking for an extra glossy finish (highly recommended!).
18. 18
    Leave the Wellington to cool for 15-20 minutes before slicing into it. This gives the mushroom filling time to firm up. Don't worry, it will still be very warm!
19. 19
    Slice with a sharp serrated knife and serve immediately.