- Prepare your vegetables: chop the onion, the carrots, and the celery. Aim for 1″ pieces. 
- Set the rack in your oven to the lower third, and heat your oven to 350°. 
- In a large, oven-safe pot, heat the oil over medium-high heat until it gets shimmery. Rub both sides of the brisket with salt and pepper (about 1 tsp of each), and brown it in the pot, turning it once. Remove the browned brisket to a plate. 
- Reduce the heat to medium. Add the onions to the pot and cook them until they turn golden-brown (about 12-15 min). Add in the carrots, celery, and garlic, and cook for another 10-12 min, stirring occasionally. Add the wine or beer, stirring well and scraping up the yummy bits from the bottom of the pot. 
- Add the chicken stock and tomatoes, and bring the pot to a simmer. 
- Return the brisket to the pot (the liquid almost certainly won’t completely cover the brisket. Don’t worry, it’s not supposed to). Cover the pot with a tight-fitting lid, stick it in the oven, and braise it for about 3 to 3 1/2 hours (until it’s fork tender).