Fifteen Kilograms of Imperfect Lemons

Chop 1kg potatoes and 1kg parsnip into 3cm cubes and place in baking dish.

Place in gratin dish.

Meanwhile, melt 85g butter in a large saucepan and mix in 85g plain flour. Gradually add 600ml milk until sauce has thickened. When thick, turn off the heat and stir in 2 tablespoons honey, 2 tablespoons mustard, and 2 tablespoons white wine vinegar. Pour over the potatoes and parsnips and bake for an hour at 180°Celsius.