Mushroom toad in the hole

Method

1. Using a stick blender, whizz the yorkshire pudding batter ingredients in a jug with a pinch of salt, then put in the fridge for at least an hour.
2. Heat the oven to 200ºC/180ºC fan/gas 6. Put the dried mushrooms in a heatproof bowl, pour in the hot water and leave to rehydrate. Put the oil and whole portobello mushrooms in a very large ovenproof dish, then cook in the oven for 15 minutes.
3. Meanwhile, pour a dash of oil into a medium pan over a medium heat and fry the red onion for about 12 minutes, stirring often, until starting to caramelise.
4. Carefully remove the mushrooms from the oven. Pour in the chilled batter, then quickly return to the oven for 15-20 minutes, reducing the heat to 180ºC/160ºC fan/gas 4 after 10 minutes.
5. For the gravy, add 1 tbsp of the cooked red onion to a smaller pan, then stir in the miso paste, mustard and flour. Slowly whisk in the wine to create a paste. Strain the rehydrated dried mushrooms, reserving the soaking liquid, then finely slice. Whisk the soaking liquid into the gravy pan, then add the sliced mushrooms and thyme leaves. Season to taste with salt and pepper, bring to the boil, then turn the heat down to a simmer.
6. When the toadstool in the hole has 5 minutes left, add the 400ml vegetable stock to the remaining cooked onion in the pan and whisk in the polenta. Bring to the boil, then turn down the heat and simmer for 1-2 minutes until thickened. Finally, beat in the butter and cheese and season with salt and pepper. Portion out the toad in the hole and serve with the cheesy polenta and gravy.