Rinse, pat dry and slice mushrooms (makes about 1 ¼ cups). In a saucepan melt butter. Add mushrooms, onion and garlic; sauté until golden, about 5 minutes.

Stir in broth, tomato paste and black pepper. Bring to the boiling point. Reduce heat and simmer, covered, for 10 minutes.

Blend cornstarch with water. Mix some of the hot mushroom sauce into cornstarch mixture and return to saucepan; cook and stir until clear and thickened. Stir in wine. Cook until hot.