Sear the brisket for about 1 minute on each side until very brown. Set meat aside on a plate.
Prepare for Cooking
Deglaze the pan with beef stock or red wine.
Line the bottom of the pan (or enameled Dutch oven or Crock Pot liner with most of the onion rings. Keep a few off to the side.
Place brisket in your cooking vessel, fat side up.
Liberally season on all sides with salt, pepper, and chili powder.
Pour the Chili Sauce or Spicy Ketchup over the brisket.
Add beef broth until liquid comes to 1/3 to 1/2 of the brisket.
Top the brisket with the sliced onion rings that you set aside.
SLOW COOKER INSTRUCTIONS
Cook on low for 8 to 10 hours.
OVEN INSTRUCTIONS
Tightly cover your enameled Dutch oven with a lid. Or, if you're using another cooking vessel without a tightly fitting lid, cover it very tightly with aluminum foil. The idea is for no steam to escape. It's important to braise the meat in lots of liquid. If that liquid evaporates and escapes into the oven, your meat will be tough.
Cook at 250 for about 60 minutes per pound. For a 6lb brisket, this will take at least 6 hours. Remember, it is almost impossible to overcook brisket, but very easy to undercook it. Leave yourself at least 8 hours. (*see note if in a hurry)
Let the brisket reach an internal temperature of 180-190. Check that the meat is fork tender. Turn off the heat.
Optimal - Allow to Rest
Remove the brisket and let rest on a board for a minimum of 45 minutes. Longer is better - this allows the brisket to reabsorb its juices and the fibers to relax! You can even refrigerate the brisket overnight in its sauces.
Do not discard any sauce.
After resting, slice the brisket against the grain.
Return the slices to the sauce. Rewarm in an oven at 170 degrees.
To cut/slice IF on a time crunch
If you are in a hurry, take the meat out about 1 hour before the expected time to finish.
Remove and place on a cutting board. The consistency should be right between slice/shred. Slice against the grain.
Put slices back into the sauce for another hour or until meat is fork tender.
When shopping for your brisket, try to get a portion that includes the fatty point (also called "2nd cut") for a moister meat.
Make your own chili sauce with 1 cup tomato sauce, 1/4 cup brown sugar, 1/4 cup vinegar, 1 tsp salt, and 1/2 tsp onion flakes.
If you cannot shred the meat, never fear: You have not overcooked it! It's just not done yet. Return to the sauces and cook for at least another hour before checking again.
If you're in a hurry, you can cook at 300 degrees. Estimate 40 minutes per pound in this case.