Season the beef brisket well with salt and pepper. Crush the thyme and rosemary together with a mortar and pestle and rub the herb mix into the beef, coating it evenly. Rub the beef well with 1 tablespoon of the olive oil.
Heat a large saute pan with 1 tablespoon olive oil over medium high heat for 2 to 3 minutes until the pan is nearly smoking. Add the beef to the hot pan and sear well on one side until browned before turning the beef over and searing the other side. When the beef has been well browned on both sides, remove from the pan and set aside.
Add the onions to the saute pan and cook them until golden brown. Add the red wine to the onions and reduce by half.
Pour the onions into a large heavy roasting pan and spread evenly across the bottom before putting the beef on the bed of onions. Add the carrots, garlic, hot beef/water and celery bundle to the beef in the roasting pan and place, uncovered, into the oven. All the combined liquid should rise only 2/3 as high as the meat is thick. Add additional water to maintain the braising liquid height.
Cook for 1 hour before turning the beef over. Cook the second side uncovered for 1 hour before covering the pan with a cover or foil and turning the oven down to 325 degrees. Continue to slowly braise the beef brisket for 1 1/2 to 2 additional hours.
Remove the pan from the oven, discard the celery bouquet and allow the beef to rest for 20 minutes before slicing and serving with some of the onion jus.