Brown the lamb: add the oil, diced lamb, salt and pepper to a large sauté pan. Sear at high heat for 3 to 5 minutes to brown the edges. Then remove from pan.
Sauté the onions: without rinsing or cleaning the pan add the diced onion and fry of for 2 to 3 minutes. Then remove from heat and set aside.
Vegetables: starting with the potatoes add the vegetables to the slow cooker. In layers place the chopped potatoes, carrots, capsicum and sliced mushrooms.
Liquids: add the chicken stock, diced tomatoes, Worcestershire sauce and tomato paste.
Flour, meat and onions: next add the plain flour, browned lamb and sautéed onions to the slow cooker. Take a wooden spoon and stir till all ingredients have combined.
Cook: place the 2 bay leaves on top of the combined stew, pop the lid on the slow cooker and turn the setting to low (cook for 8 hours) or high (cook for 4 hours).
Serve and enjoy: once cooked, remove the slow cooker lid, discard the bay leaves and turn the heat off. Use a ladle to portion the lamb stew into bowls, garnish with finely chopped parsley and cracked black pepper (optional). Provide fresh bread for dunking.