Step 1

Place the beef, bay leaves, peppercorns, vinegar, sugar and 4 cups (1L) of water in a large heavy based pot over medium heat. Bring to the boil. Add the celery, carrot and shallots. Cover and reduce heat to low. Simmer for 2 hours or until beef is tender. Remove from heat. Transfer beef to a plate. Thinly slice.

Step 2

Meanwhile, cook the potato in a saucepan of boiling water for 12-15 mins or until tender. Drain and return to the saucepan over low heat. Shake the pan to remove any excess moisture. Add butter and buttermilk. Mash until smooth. Remove from heat. Season.

Step 3

Place finishing sauce, mustard and 1/2 cup (125ml) cooking liquid in a saucepan over low heat. Cook for 5 mins or until mixture is heated through.

Step 4

Divide the mash among serving plates. Top with sliced silverside, carrots, onions and mustard sauce. Sprinkle with parsley and spoon over some of the braising liquid to serve.