In a skillet set over moderate heat cook the scallion in the oil, stirring, for 2 to 3 minutes, or until softened. Add the mushrooms and salt and pepper to taste and cook them, stirring occasionally, for 5 minutes. Add the garlic and toss 1 minute. Add the wine and reduce by half. Add the broth and tomato paste and simmer 3 minutes, stirring. Add the cream and simmer until lightly thickened. Stir in the herbs. Serve the saute over baked or grilled polenta or as a sauce for pasta.