Place mushrooms in a medium bowl; add warm water to cover and soak for 30 minutes.
Meanwhile, mix simmering sauce ingredients in a small saucepan.
Squeeze mushrooms dry. Cut off and discard the stems. Add mushroom caps to sauce, Bring to a boil over medium-high heat. Reduce heat to medium-low and simmer 15 to 20 minutes or until liquid has almost all evaporated and mushrooms are well-seasoned. Serve warm or at room temperature. Divide with remaining liquid between 2 small serving bowls.