Melt the butter in a frying pan then add the sugar. Place the rhubarb in the pan and cook quickly until just tender. Remove the rhubarb from the pan and set aside to cool.
Deglaze the frying pan with the port and set aside.
Mix together the oil, lemon juice and mustard and season with sea salt and freshly ground black pepper. Make a loose ball of the salad leaves in the palm of your hand, place in the centre of each plate and dress with the olive oil mixture.
Make criss-cross patterns around the leaves with the rhubarb batons, sprinkle the goats’ cheese over and around the rhubarb and finish with a drizzle of the port glaze.