Soak the dried mushrooms in a quart of hot water for several hours. Drain, reserving the liquid. Wash mushrooms under running water, one by one, and trim off the hard stems. Cut in wide strips. Strain the liquid through cheesecloth, there should be about 2 cups. Simmer the liquid until it is reduced by slightly more than half. Thickly slice the fresh mushrooms. Saute the minced onion in butter until they are transparent, then add the sliced fresh mushrooms and toss over high heat until they have released their excess water and it is starting to evaporate. Season with thyme, salt and pepper to taste. Add the soaked mushroom strips and reduce the heat to medium-low. Gradually whisk the mushroom liquid into the sour cream, and add this mixture to the mushrooms. Simmer gently, stirring often, for 15 to 20 min. Stir in the brandy and sherry. Boil the noodles in salted water until they are just tender, but not yet soft. Serve with stroganoff sauce, and a crisp salad.