Trim all of the fat and silverskin from the brisket; season with salt and pepper(omit if using Corned Beef), and place in a 9×12″ baking dish.
Cover the meat with the onion slices
Combine chili sauce,brown sugar,garlic 7 beer. Pour over the brisket & cover toghtly with aluminum foil.Bake for 3 1/2 hours at 350 degrees.
Remove the aluminum foil and bake uncovered for another 30 minutes.Baste the meat several times during his period.
Remove the meat to a serving platter, and cover with foil. Skim any excess fat from the cooking liquid.Add enough water to make 1 cup.Pour the liquid in a small saucepan over medium heat. Make a slurry of flour by adding a small amount of water.Add to the liquid in the saucepan and bring to a boil, stirring constantly until it reaches gravy consistency
Slice the meat thinly. Serve it with boiled Potatoes,Carrots,and small wedges of Cabbage.