Heat your oven to 200°C/Fan 180°C/Gas 6. Crumble the stock cube into a measuring jug and stir in 600ml boiling water. Add the dried porcini and set aside to steep.
Peel the beetroot and finely slice into matchsticks. Pop in a bowl with a large pinch of salt. Scrunch together. Pour in 2 tbsp brown rice vinegar. Stir and set aside to pickle.
Scrub the potatoes and chop them into 1cm cubes. Chuck in a large pan and cover with boiling water. Add a pinch of salt. Bring to the boil and simmer for 5 mins. Drain and leave to dry in the colander.
While the potatoes are boiling, thickly slice the mushrooms. Peel and grate the garlic. Peel and thinly slice the onion. Heat ½ tbsp oil in a heavybased pan over a medium heat. Tip in the diced chicken leg. Fry for 5-6 mins, stirring occasionally, till golden on all sides. Lift the chicken, using a slotted spoon, onto a plate.
Pour ½ tbsp oil into the pan. Add the onion, garlic and mushrooms. Cook for 4-5 mins till the veg have softened. Add the chicken and any resting juices from the plate. Pour in the porcini and porcini-infused stock. Bring to the boil, then turn down the heat. Cover and simmer for 30 mins.
Tip the potatoes onto a baking tray lined with baking paper. Drizzle over 1 tbsp oil and season. Roast for 20-30 mins till crisp and golden. Turn the potatoes after 10 mins.
Finely chop the dill stalks, saving the soft frondy leaves for later. Pour 100ml of the cream into a bowl. Ladle a couple of spoonfuls of the stock from the chicken pan into the cream. Add the dill stalks and mix, then pour into the pan. Cook for 2 mins till warmed through. Taste and add more salt and pepper if you think it needs it.
Roughly chop the dill leaves. Add half to the chicken and the remainder to the pickled beetroot. Serve the chicken and beetroot with the roast potatoes on the side.