# Pre-heat oven 150°C/gas mark 2. Place all the ingredients except the shin steaks, tomato purée and flour into a container large enough to hold everything. Mix together then add the shin steaks, making sure the liquid just covers the steaks. Cover and leave for a couple of hours to marinate.
# In the meantime make your shin stock. Brown the trimmings with a little oil in a hot pan then tip into a large stockpot with a few onions, carrots and celery sticks. Cover with water and simmer for a couple of hours before straining. Alternatively you can use ready-made stock.
# Remove the steaks from the marinade, pat dry with kitchen paper and dust with a little four. Heat the oil in a frying pan and brown the steaks on all sides, seasoning generously with freshly ground black pepper and a little sea salt.
# Transfer the steaks to a casserole; add the marinade liquid, tomato purée and enough beef stock to cover the steaks completely. Cover with a lid or foil and cook gently in the oven for 2 hours. The meat should be meltingly tender when pushed gently with a fork.
# Meanwhile make the potatoes. Line an ovenproof dish with baking parchment then select the nicest large slices of potato for the top and set aside. Soak the porcini mushrooms in warm water, drain through a fine sieve and reserve the stock. Rinse the mushrooms thoroughly in cold water several times.
# Fry the bacon in a little butter until crisp and brown then remove with a slotted spoon and set aside to drain on kitchen paper. In the same pan fry the mushrooms, onion and garlic in a little more butter then drain as before.
# Crush the remaining potatoes together with the double cream and a little mushroom stock, seasoning generously. Fold in the onion, mushrooms, bacon and parsley and line the baking dish with the mixture. Arrange reserved potato slices nearly across the top, brush with butter and bake for 40 minutes at 160°C/gas mark 21/2, or until the top is crisp and golden.
# Remove the steaks carefully from the casserole and set aside on a warm plate covered with foil. Pour the cooking liquid into a pan, straining and skimming off any grease. Boil rapidly until reduced down to a good sauce consistency and you are now ready to plate up.