In a small bowl, cover the dried mushrooms with boiling water. Set aside and leave to soak for 30 minutes.
Heat the oil in a large non-stick frying pan. Add the onion, celery and garlic and cook until softened. Add the paprika and cook for a further 30 seconds. Stir in the fresh mushrooms, cook for 1 minute, then add the brandy, if using. Continue cooking until the mushrooms start to soften.
Drain the rehydrated porcini mushrooms, reserving 100ml of the soaking liquid. Add both to the pan, bring the mixture to the boil, then simmer for 2-3 minutes. Stir in the cream alternative, soy sauce, chopped thyme and lemon juice. Season.
Griddle the ciabatta halves for 1-2 minutes on each side. Top with the mushrooms, garnish with the extra thyme sprigs and serve.