Put the cabbage, pears, ginger, stock and
vinegar into a pan. Bring to the boil, then
reduce heat. Cover, then gently cook, stirring
occasionally, for 40 mins. Stir in the walnuts.
Split the pork fillet almost in half down its
length, then open out like a book. Rub on all
sides with the oil and smear with mustard.
Grill for 15 mins, turning once, until the pork is
browned and just cooked. Cover with foil, rest for
2 mins, then slice and serve with the cabbage.