Place Brisket On A Large Piece Of Heavy Duty Foil. Season To Taste With The Pepper, Garlic Powder And Celery Seed. Spread With Soup And Top With Inion Slices. Wrap Brisket Tightly In The Foil And Refrigerate Overnight. To Bake Let Stand At Room Temperature For 1 Hour. Place In Baking Pan And Bake At 325 Deg F. For 2 1/2 Hours. Uncover And Sprinkle With Paprika. Return To Oven And Bake 1/2 Hour More. Slice Thinly Across The Grain To Serve.