In a large skillet, heat oil over medium-high heat. Saute onion in oil and cook, stirring regularly, for about 10-15 minutes (or until soft, but not brown).

Use a slotted spoon to remove onions from skillet and place them in a large rectangular baking dish (or a Dutch oven). Set aside.

Cut about 6-8 slits in the top of your brisket and place a garlic clove in each slit. Tuck it down in there so that it doesn’t fall out!

Heat the skillet over high heat and sear the brisket on each side. This should only take a few minutes per side, because you just want to get a nice dark color on each side of the meat – you are not trying to cook it all of the way through!

Once both sides of the brisket are browned, place the brisket on top of the onions in the baking dish. Season the top of the brisket with salt and pepper, to taste. Spread ketchup over top.

Cover brisket with foil (or place lid on Dutch oven).

Bake, covered, at 225 degrees F for 6 hours.

When the brisket comes out of the oven, do NOT cut it right away. Allow the meat to cool and rest.

When it’s cool, put the whole dish in the refrigerator and allow the meat to sit in the onion gravy overnight.

The next day, you will notice that the fat has solidified on top. Remove this white fat as much as possible.

Slice the brisket against the grain while it’s cold. You may need an electric knife.

Place the sliced meat back in the onion gravy. Put it back in the refrigerator overnight (or you can even freeze it at this point), and allow the meat to soak up the gravy again.

When you’re ready to serve the brisket, cover it with foil and reheat it in a 350-degree oven until warmed through.