Fry off the steak and onion in the lard, then add the plain flour and stir. Now add the Guinness, stock and tomato puree and stir. Then add the bay leaf and mushrooms and stir well. Place into the oven and cook overnight. When cooked, place into the fridge to cool. Make up the suet pastry and line a pudding basin with the pastry. Fill the bowl with the chilled beef mixture and line the top with pastry, then cover leaving space for the pastry to rise. No place the bowl into the oven on steam for around 2 and a half to 3 hours. Once ready, turn out and cut into 8 and serve with mashed potato and vegetables.