| Trim fat from brisket; place in a 13- x 9- x2-in baking dish. Sprinkle top of brisket with pepper; arrange onion rings over brisket. Combine chili sauce and next 3 ingredients; stir well, and pour over brisket. Cover and bake at 350 for 3 hours.
Uncover and bake an additional 20 minutes or until brisket is tender. Place brisket on a serving platter, reserving cooking liquid. Set brisket aside, and keep warm.
Pour 1 1/2 cups cooking liquid into a small saucepan. Place flour in a small bowl. Gradually add water, blending with a wire whisk; add to cooking liquid. Bring to a boil and cook 2 minutes or until gravy is thickened, stirring constantly. Serve gravy with brisket. Sprinkle with pepper, and garnish with tomato slices and parsley springs, if desired.