Heat a good glug of olive oil in a frying pan over a medium heat. Once hot, add the onion and fry for 8-10 minutes, until soft and translucent. Add the thyme and flour, stir well and continue to fry for a further 2-3 minutes, to cook off the flour.

Meanwhile, combine the dried porcini mushrooms, vegetable stock and white wine in a large saucepan. Bring to a boil over a medium-high heat, then reduce the heat to a simmer and cook for 6-8 minutes, or until the mushrooms are very soft. Remove from the heat and stir through the miso paste until mostly dissolved.

Combine both the onion and mushroom mixtures in a blender. Blend until completely smooth, adding a little more vegetable stock if you would prefer it slightly thinner. Taste and adjust the seasoning, if needed.

Transfer the gravy back into a pan and reheat until piping hot before serving.