1. Preheat oven to 325 degrees F. Trim any remaining excess fat from brisket. Season both sides of brisket well with salt and pepper.
2. Heat 2 tablespoons olive oil in a heavy casserole over medium-high heat. Add brisket, and brown very well, 4 to 5 minutes per side. Transfer to a plate, and set aside.
3. Reduce heat to medium low, add remaining tablespoon olive oil, onions, and garlic, and cook, stirring frequently, until quite brown and very soft, about 25 minutes. Add red wine, raise heat to high, and bring to a boil. Cook about 2 minutes, scraping up the brown bits on the bottom of the pot. Add carrots, celery, and tomatoes, and stir well to combine.
4. Return brisket to the pot, spooning some liquid and vegetables over it. Cover, and transfer to the oven. Cook until very tender, about 3 hours, carefully turning meat after 1 1/2 hours.
5. Let cool slightly, and remove brisket, being careful not to shred it. Transfer sauce and vegetables from the pot to a food processor, and process until very smooth. Adjust seasoning with salt and pepper if necessary. If preparing the day before, return brisket to pot, pour sauce over, and refrigerate. If serving right away, return sauce to the pot. Slice meat across the grain into 1/4-inch-thick slices, and place in sauce. Warm over medium-low heat for about 5 minutes.
6. If refrigerated overnight, remove brisket from refrigerator, and slice across the grain. Add sliced meat to sauce, and reheat over medium-low heat until warmed through, about 30 minutes.

Yield: 10 servings