Mushroom steak and chunky fries with beurre-less blanc sauce

By Mary McCartney From Saturday Kitchen Ingredients For the chunky fries 700g/1lb 9oz russet potatoes, peeled and cut into 1cm/½in-thick batons 3 tbsp vegetable oil flaky sea salt and freshly ground black pepper For the beurre-less blanc sauce 3 shallots, …