Rehydrate the dry mushrooms by soaking them in 2-3 cups of warm or room temperature water for 30 minutes.
Heat the oil in a large saucepan.
Add the onions, carrots and celery. Season with some salt and pepper and cook, stirring often, until the onions are translucent, about five minutes.
Add the garlic and saute another minute or two.
Add the mushrooms. Be sure to drain the dry mushrooms but don't throw away the stock from rehydrating them. In fact, I used the stock to make my cashew paste too, instead of water.
Saute the mushrooms well. Add the wine and cook for a few minutes until the alcohol has evaporated and the mushrooms look caramelized. Stir in the tomato paste, tamari, thyme and rosemary and add about a cup of the mushroom stock.
Bring the stew to a boil, cover, and cook over low heat for 15 minutes or until the mushrooms are tender. Some of the dry mushrooms will remain a little chewy-- you can cook for longer if you want them to soften up. Be sure to add more stock if it dries up.
Stir the cashew paste into the osso buco, and add salt and pepper if needed. Finish by stirring in the gremolata.
Serve hot with risotto.