For the Brisket:
5-6 lb point-cut beef brisket
kosher salt and ground black pepper, to taste
3-4 T. all-purpose flour
2 T. EVOO
5 large Spanish onions, cut into thin wedges
8 cloves garlic, smashed
3/4 C. tomato paste
3 C. full-bodied red wine
1 t. sugar
4 leafy inner stalks celery
2 sprigs fresh rosemary (6-8 inches)
2 bay leaves
1 pound carrots, halved crosswise
For the crust:
1 clove garlic, smashed
kosher salt
1 6-oz piece fresh horseradish, peeled
1/2 C. roughly chopped fresh parsley
2-3 T. Dijon mustard
1. Prepare the brisket: Preheat the oven to 350. Generously season the brisket with salt and pepper, then coat with the flour in a large bowl. Heat the olive oil in a large Dutch oven or ovenproof pot over med-high heat. Brown the brisket on all sides, about 10 minutes. Transfer the meat to a plate.
2. Add the onions and 2 tsp salt to the pot and cook, stirring until soft, about 5 minutes. Add the garlic, and cook, stirring until the onions are caramelized, about 10 more minutes. Add the tomato paste and cook about 5 more minutes. Add the wine and 1 C. water, scraping up the browned bits from the bottom of the pot. Stir in the sugar. Reduce heat to maintain a low simmer.
3. Tied the celery, rosemary and bay leaves together with kitchen twine and add to the pot along with the brisket and carrots. Cut a round of parchment paper to fit inside the pot; place directly on top of the liquid, then cover with the lid. Transfer to the oven and cook 3 hours, 30 minutes.
4. Meanwhile, make the crust. Mince and mash the garlic with 1 tsp salt. Coarsly grate the horseradish. Chop the parsley with the horseradish and garlic paste until the mixture is moist.
5. Remove the pot from the oven, discard the parchment and transfer the meat to a rimmed baking sheet. Increase the oven temp to 375. Brush the top of the brisket with the mustard, then pat with the horseradish mixture. Return the meat to the pot and bake, uncovered, until the crust is golden, 30-35 minutes.
6. Transfer the brisket to a cutting board. Discard the celery-herb bundle and skim the fat from the braising liquid; thin the remaining liquid with water, if desired. Slice the meat against the grain. Serve with the carrots, onions and braising liquid.