Heat the olive oil in a large, heavy-based casserole and cook the meat, onion and garlic together for 2 minutes.
Add the water, ginger, saffron and salt and pepper to taste. Cover and cook for 15 minutes.
Stir in the chestnut mushrooms (along with the porcini mushrooms in white truffle paste or white truffles, if using), and the parsley and coriander. Allow to simmer for a further 5–7 minutes over a low heat until the sauce has reduced.
Transfer to a serving platter, with the meat arranged around the truffles and garnished with chopped coriander or flat-leaf parsley.