01 - Preheat oven to 325°F. Pat brisket dry with paper towels and season all sides evenly with kosher salt and black pepper.
02 - Heat olive oil in a large Dutch oven over medium-high heat. Sear brisket until browned on both sides, approximately 4 to 5 minutes per side. Transfer brisket to a plate.
03 - Reduce heat to medium. Add sliced onions, carrots, and celery to the pot and cook while stirring until onions are caramelized and softened, about 10 minutes. Add minced garlic and cook for 1 more minute.
04 - Incorporate tomato paste and cook for 2 minutes. Pour in red wine, scraping browned bits from the pot. Add beef broth and Worcestershire sauce, then bring mixture to a simmer.
05 - Return brisket to the pot, placing it fat side up. Add thyme, rosemary, and bay leaves. Cover with a tight-fitting lid and transfer to the preheated oven.
06 - Braise brisket in the oven for 2½ to 3 hours, until fork-tender.
07 - Remove brisket and let rest on a cutting board for 10 minutes. Skim excess fat from sauce, discard herb stems and bay leaves, and spoon onion sauce over sliced brisket for serving.