Roast Mushroom and Kimchi Sourdough Sarnies

Method

1. There’s no need to preheat your oven for this – unless it’s a non-fan oven that takes a while to heat up.
2. Trickle the olive oil into a roasting dish and spread it around with a brush. Add the mushrooms, gill side down and use the brush to get some oil on the top of them. Add the onion rounds to the dish, and oil these too. Season everything well with salt and pepper.
3. Put the roasting dish into a cold oven and set it to 180°C Fan/200°C/Gas 6. Cook for 20 minutes, or until the mushrooms are well shrunken and darkened and the onion is soft (it might take a little longer in a non-fan oven). 
4. Take the dish out and use tongs to flip everything over. Season again and return to the oven for 15–20 minutes or until everything is completely tender and nicely caramelised.
5. Meanwhile, toast the sourdough slices (or rolls).
6. Take one slice of toasted sourdough (or toasted roll base) and lay a whole mushroom on it. Put a spoonful of kimchi/kraut on top and add a round or two of caramelised onion. Cover with a second mushroom and a little more kimchi/kraut, then top with another layer of onion. 
   
7. Repeat with the other toast, mushrooms, kimchi/kraut and onion to make the second sarnie. Squeeze the lids on top and serve, with the rest of the kimchi/kraut on the side.