Fill a large baking tin with the rhubarb, sugar, cinnamon, cardamom, vanilla beans and seeds. Halve the mandarins, squeeze them over the rhubarb and add the peels. Stir thoroughly and cover with aluminium foil. Place in an oven preheated to 180°C (350°F/ Gas 4) for approx. 20 minutes and stir occasionally. Fill two
1-