Braised Brisket with Orange Horseradish Gremolata

For the brisket

• 3½-4 lb beef brisket, first-cut, fat trimmed to a very thin layer
• kosher salt and freshly ground pepper
• 1 tbsp olive oil
• 2 large yellow onions, thinly sliced
• 6 garlic cloves, chopped
• 1 (14.5 oz) can diced tomatoes
• ⅓ c balsamic vinegar
• ¼ c packed light brown sugar
• 2 tbsp tomato paste

Gremolata

• ¾ c parsley, finely chopped
• 2 tbsp fresh horseradish, peeled and finely grated
• Zest of 1 lemon
• Zest of 1 large orange

Preheat broiler to high. Pat beef dry with paper towels and season with salt and pepper. Place in large roasting pan and broil, turning once, until browned on both sides, 8 to 10 minutes. Transfer brisket to a plate. Turn off the broiler and turn the oven to bake at 300°F.

Heat oil in roasting pan over two burners on medium-high heat. Add onions and garlic and cook, stirring occasionally, just until the onions begin to soften, about 4 to 5 minutes. Stir in tomatoes, 1 cup water, vinegar, brown sugar, and tomato paste and bring to a simmer. Return brisket to pan and spoon onions on top. Liquid should come about halfway up brisket; add more water as needed. Cover tightly with aluminum foil.

Return to oven and bake until brisket is very tender when pierced with a fork, about 3 hours. Transfer brisket to a carving board. Use a slotted spoon to transfer the onions to a serving platter.

Meanwhile, make the gremolata: In a small bowl, combine parsley, horseradish, lemon zest, and orange zest. Set aside.

Bring cooking liquid to a boil and cook, uncovered, until reduced by about half, about, 12 to 15 minutes. To serve, slice brisket across the grain into thin slices and transfer to a platter. Spoon as much sauce as you like over the brisket and sprinkle with gremolata.