In a large skillet or saute pan, melt the butter over medium-high heat. Add the shallots and garlic, and cook, stirring, for 2 minutes. Add the mushrooms, salt, and white pepper and cook, stirring, until the mushrooms begin to caramelize and all the liquid has evaporated, about 20 minutes. Add the wine, soy sauce, balsamic vinegar and Worcestershire and cook, stirring to deglaze the pan and until the liquid has all evaporated, about 5 minutes. Remove from the heat and let rest while assembling the other ingredients.
Yield: 3 cups