Lentil, leek & mushroom stew with potato & celeriac mash

1. Cut the potatoes into equal-sized chunks. Put them into a large saucepan with just enough water to cover, add a pinch of salt and bring to the boil. Cover and simmer for 20 minutes. Add the celeriac and simmer for a further 5 minutes, until both are tender. Drain and return
to the pan, off the heat. Add the butter and season. Mash well using a potato masher, replace the lid and keep warm.

2. Meanwhile, heat the oill in a large frying pan over a medium heat. Add the leek, season and cook for about 5 minutes until browning and softened, stirring regularly. Transfer to a bowl. Set aside.

3. Add another 1 tsp oil to the pan (no need to clean it). Add the mushrooms and cook over a high heat until golden, then return the leeks to the pan. Reduce the heat, then stir in the lentils and stock. Mix together and heat through gently. Divide the mash between 2 plates and spoon the lentil and mushroom mixture over the top.