Preheat the oven to 180 celsius (350 Fahrenheit). Place all of the ingredients for the chermoula mushrooms, except the mushrooms, in a food processor. Process until a paste forms. Line a large baking tray with baking paper and score the mushrooms with a cross, making sure not to cut all the way through the mushrooms. Place the mushrooms top side down in the tray and spoon 3/4 of the chermoula over the mushrooms, making sure the mushroom is well coated. Baked for 25 to 30 minutes, or until the mushroom is juicy and tender.
Meanwhile, to make the Persian Spiced Buckwheat, toast the buckwheat in a large frying pan over a medium heat for around 5 minutes, or until lightly golden and smelling toasty. Place the water, spices, sea salt and dates in a saucepan and bring to a boil. Add the buckwheat, stir and cover and cook for 15 minutes, or until the buckwheat is tender. Keep warm until ready to serve. Just before serving add the pomegranate seeds and pistachios.
To make the preserved lemon cashew cream place the ingredients in a high speed blender and process until smooth, adding more water or almond milk as needed to form a smooth paste.
To serve divide the Persian buckwheat and mushrooms between 4 plates. Top the mushrooms with remaining chermoula. Serve with mixed leaves or roasted baby carrots and top with the preserved lemon cashew cream.