1. Place brisket in a shallow pan.
2. Season with salt, pepper and garlic powder.
3. Pour French dressing over beef.
4. Marinate in refrigerator overnight or for several hours. Turn meat at least twice.
5. Place brisket in roasting pan and roast at 325 ºF. for 30 minutes per pound.
6. About half-way through cooking tine, remove from oven, and add chili sauce, wine and onions.
7. Return to oven to finish roasting.
8. When done, remove meat from pan (reserving gravy), cool and slice.
9 Add mushrooms if desired and return sliced meat to pan and pour gravy over it.
10. Bake at 325 ºF. for an additional 30 minutes or until hot all the way through.