Place the porcini in a bowl and pour over 500 ml of boiling water and leave them to soak. Heat the oil in a large pan and add the onion. Cook over a med-high heat, stirring constantly until the onion is an even nutty brown, careful not to let it burn.
Add the carrot and celery and turn the heat to low, then add the tomato puree and flour and cook, stirring regularly for 5 minutes
add the stock or water, wine, sherry,tamari,the mushrooms and their soaking liquid, and the herbs, peppercorns and all spice.Turn up the heat to medium, cover and simmer for 20 minutes.
strain through a fine sieve, cool and refrigerate until needed.