Drain tofu on paper towel. Meanwhile, melt 1 tablespoon of the butter in a large skillet. Sauté chopped Onion. Add Mushrooms to onions in skillet and sauté until tender. Add salt, pepper, chives and garlic powder. Remove mixture from pan. Slice drained tofu into long strips, about 3 inches long, 3/4 inches wide and 1/2 inch deep. Fry tofu on both sides in remaining 1 tablespoon butter until golden brown. Add mushroom-Onion mixture to tofu. Immediately before serving, add sour cream, tamari soy sauce and cooking sherry. Serve over noodles.