Preheat the oven to 160°C.
Heat 2 tablespoons of oil in a flameproof casserole and brown lamb shanks for 6 minutes until golden.
Remove lamb, add remaining oil, and fry sliced onion and garlic for 4 minutes until soft.
Whisk flour and wine into a smooth paste in a bowl.
Add stock to the onions, stir in the wine paste, and bring to the boil.
Stir in redcurrant jelly and chopped rosemary until the sauce thickens.
Return lamb to the pan, season, cover, and bake for 2 hours until tender.
Boil carrots, parsnips, and turnips in salted water for 10 minutes, then drain.
Stir one third of the vegetables into the lamb casserole.
Fry the remaining vegetables in butter for 5 minutes until browned and season.
Serve lamb with sauce, mixed vegetables, and a garnish of fresh parsley.