Braised oxtail with orange gremolata

1.5kg oxtails, diced into 5cm pieces
2 tablespoons plain flour
2 tablespoons olive oil
1 medium brown onion (150g), chopped coarsely
2 cloves garlic, crushed
½ cup (125ml) sweet sherry
400g can crushed tomatoes
1 cup (250ml) beef stock
1 cup (250ml) water
4 sprigs fresh thyme
2 bay leaves
10cm strip orange rind
4 medium tomatoes (600g), chopped coarsely

Orange gremolata
¼ cup finely chopped fresh flat-leaf parsley
1 tablespoon finely grated orange rind
1 gloves garlic, crushed

Preheat oven 160
Coat oxtail in flour, shake off excess. Heat half of the oil in large casserole dish, cook oxtail , in batches, until browned all over.
Heat remaining oil in same dish, cook onion and garlic, stirring, until onion softens. Return oxtail to dish with sherry, undrained tomatoes, stock, the water, herbs and rind, cook, covered, in oven about 3 hours or until oxtail is tender. Stir in chopped tomato.
Meanwhile combine ingredients for orange gremolata in small bowl.
Serve oxtail sprinkled with gremolata on mashed potato