1/4 pound portobello mushrooms, thinly sliced
3 tablespoons butter
1/2 cup port wine
2 tablespoons sour cream
1/2 teaspoon cornstarch
salt and ground black pepper to taste
Heat butter in a large heavy skillet over medium-high heat. Saute mushrooms until soft and lightly browned, about 2 minutes. Stir in port wine, and let simmer for 2 minutes; remove from heat. In a small bowl, mix together sour cream and cornstarch. Stir into mushroom mixture until smooth. Return to heat, and stir until thickened and smooth. Season to taste with salt and pepper.