Place the dried porcini mushrooms in a heatproof bowl and pour over the boiling water. Leave them for 20 minutes to soften.
Lift the mushrooms out of the liquid, roughly chop them, and set them aside. Strain the soaking liquid through a fine mesh strainer lined with kitchen paper or a coffee filter to remove any grit.
Heat the olive oil in a Dutch oven or large heavy-bottomed pan over medium-high heat. Brown the beef in batches until well colored on all sides.
Lower the heat to medium. Add the onion and cook for 5 minutes until softened. Add the carrot, fresh mushrooms, and garlic. Cook for another 4 to 5 minutes.
Stir in the tomato paste and cook for 1 minute. Add the flour and stir for another minute so it coats the beef and vegetables.
Pour in the strained porcini liquid and scrape the bottom of the pan. Add the beef stock, stock cube, chopped porcini mushrooms, thyme, bay leaves, black pepper, and Worcestershire sauce.
Bring the filling to a gentle boil, then lower the heat. Cover loosely and simmer for 2 to 2½ hours, until the beef is soft.
Remove the lid near the end if the gravy is thin. Continue cooking until it coats the back of a spoon.
Stir in the parsley and add salt if needed. Remove the thyme stems and bay leaves.
Transfer the filling to an 11 x 7-inch, or 27 x 19 cm, oval pie dish or a 10-inch, or 25 cm, round pie dish. Leave it to cool fully.