Potato & porcini gratin recipe - Recipes - BBC Good Food

Heat the oven to 190C/fan 170C/gas 5.

Soak the mushrooms in 300ml boiling water until soft.

Meanwhile, peel the potatoes and slice as thinly as possible, this is easiest with a mandolin. Put potatoes in a bowl of cold water to prevent them discolouring.

Heat a knob of butter and 1 tbsp olive oil in a frying pan and fry the sliced mushrooms, crushed garlic and thyme until tender. Drain the porcini, reserving the soaking liquid, roughly chop, add to the pan and cook for a further couple of minutes. Season well.

Butter an ovenproof dish and arrange the potato and mushroom mixture in layers. Pour over the vegetable stock and the porcini soaking liquid. Dot with butter and cook Butter an ovenproof dish and arrange the potato and mushroom mixture in layers. Pour over the vegetable stock and the porcini soaking liquid. Dot with butter and cook in the lower shelf of the oven for about 2 hours 10 mins until the potatoes are tender and the top is golden.