1. Put the ginger, cloves, and black peppercorns in a tea ball or tea bag, or tie into a piece of cheesecloth and stir into a bowl with the remaining ingredients.
2. Cover and marinate 6 hours to overnight, stirring once or twice if possible.
3. Drain in a colander and bake 25 minutes on a rack over an oiled cookie sheet in a preheated 375°F oven.
4. Squeeze the mushrooms in a few layers of paper towels to get rid of the excess liquid.
Serve hot as a side dish, or use in recipes that call for meat.