Preheat your oven to 350°F (175°C). Choose a large roasting pan that comfortably fits your brisket.
Sauté the onions. In a large skillet, heat a splash of olive oil over medium heat. Add the sliced onions and cook until softened and golden, about 10–15 minutes.
Build the sauce. Add the cherry tomatoes, brown sugar, ketchup, chutney, soy sauce, mustard, garlic, salt, and pepper to the onions. Stir well and let it simmer gently for 5–10 minutes to meld the flavors.
Season the brisket. Pat your brisket dry and rub generously with salt and pepper. Heat a bit of olive oil in a large pan and sear the brisket on all sides until browned.
Assemble. Place the seared brisket in your roasting pan. Pour the sauce mixture evenly over the top, making sure it’s well coated.
Roast. Cover the pan tightly with foil and place it in the oven. Bake for about 3 hours, checking occasionally to make sure nothing is burning.
Rest and slice. Once the brisket is tender, remove from the oven. Let it rest for 10–15 minutes, then slice against the grain..
Finish and serve. Spoon the sauce over the sliced brisket and serve warm. It’s perfect for Shabbat, holidays, or any time you need to impress a hungry table