Preheat the oven to 160C/325F. Mix the flour and mustard powder together, then put on a plate. Dip the rabbit joints in the flour mixture; reserve the excess flour.

Heat the butter and oil in a heavy flameproof casserole and brown the rabbit. Transfer to a plate. Stir in the onion and cook until soft.

Stir any reserve flour mixture into the casserole, cook for 1 minute, then stir in the beer, stock and vinegar. Bring to the boil and add the sugar and pepper. Simmer for 2 minutes.

Return the rabbit and any juices that have collected on the plate to the casserole, cover with a tight-fitting lid and cook in the oven for 1 hour.

Stir the mustard and salt to taste into the casserole, cover again and cook for a further 15 minutes.

To finish, heat together the butter and oil in a frying pan and fry the breadcrumbs, stirring frequently, until golden, then stir in the herbs.

Transfer the rabbit to a warmed serving dish and sprinkle the breadcrumb mixture over the top.