Prepare your brisket: Place your total measured amount of salt [see Note] in a small bowl. Trim your brisket, if necessary, so that only a thin layer of fat remains — about 1/8- to 1/4-inch thick. Season it generously on top with salt from the bowl and many grinds of black pepper.
Brown your brisket: Heat a large Dutch oven (this is a 6.5-quart oval; see Note about size options) over high heat with 1 to 2 tablespoons of oil until very hot. Place the whole brisket (if it fits) or the first half of your brisket (if you need to divide it) seasoned side-down into the hot pan then season the second side (now facing up) generously with more salt from the bowl and pepper. Cook until crusty and well-browned on both sides, about 5 to 7 minutes per side, repeating with the second half of brisket if you needed to divide it. Transfer to a plate to rest.
While the brisket browns, prepare your onions: Halve and peel each onion, and slice a generous 1/4-inch thick. You can make quick work of this with your food processor’s slicing blade, should you have one.
Cook the onions: Add the onions to your empty pot, season with salt from the bowl and pepper, and cook, stirring frequently, until the onions have softened and developed a rich brown color, 10 to 15 minutes. Add the garlic and cook for another minute.
Prepare the braise: Remove the pot from the heat. If you need to transfer the onions and garlic to an ovensafe casserole dish, do so now. Place the browned brisket on the onions and pour any juices that accumulated on the plate over it, plus 1 1/2 cups (355 ml) of water. Spread the tomato paste over the top of the brisket as if you were icing a cake. Sprinkle the brisket with additional black pepper and any salt you have left over in your dish. Scatter the carrots in the pan. Cover the pot (or use foil if your pan doesn’t have a lid) and transfer to the oven.
Braise your brisket, choosing your next directions based on when you plan to serve it:
1st schedule: Braise your brisket to serve today: Let the brisket cook, untouched, for 1 1/2 hours then remove from the oven. Carefully transfer the brisket to a cutting board. Using a very sharp knife, thinly slice the brisket across the grain into approximately 1/8-inch to 1/4-inch thick slices. Return the slices to the pot, leaning them slightly so that you can see a bit of the top edge of each slice. If the liquid looks low — ideally, we’d like the liquid 1/3 to halfway up the meat — add another 1/2 cup (120 ml) water at this time. Replace the lid on the pan and return it to the oven for an additional 1 1/2 to 2 1/2 hours. The brisket is done when you can easily pull a slice apart with a fork.
2nd schedule: Braise your brisket to serve tomorrow or the next day: Let the brisket cook, untouched, for 3 hours then remove from the oven. If the liquid looks low — ideally, we’d like the liquid 1/3 to halfway up the meat — add another 1/2 cup water at this time. The brisket is done when you can easily pull a slice apart with a fork. If it’s not done yet, return it to the oven for another 30 to 60 minutes, i.e. check at 30 for doneness and add final 30 minutes only if necessary.
Chill brisket overnight, or for two nights: Transfer brisket, covered, to the fridge.
About 1 hour before you plan to serve the brisket: Heat oven to 350°F (175°C). Remove the lid from the pot and use a spoon to remove any solidified fat from the top of and around the meat. Carefully transfer the brisket to a cutting board. Using a very sharp knife, thinly slice the brisket across the grain into approximately 1/8-inch to 1/4-inch thick slices. Return the slices to the pot, leaning them slightly so that you can see a bit of the top edge of each slice. Place lid back on pot and warm in oven for 35 to 45 minutes, until slices are hot throughout and the liquid is bubbling.
To serve (either cooking schedule): Serve the sliced brisket, spooning onions and sauce from the pan over each plate.
Notes:
Let’s talk about timing: Braised brisket is good on the first day but it’s excellent on the second and third days. I always make it in advance when I can. Serving it on the second or third day also allows us to easily de-fat the braise. However, I’m sharing here two schedules just in case you need to make it the day you’re serving it.
Let’s talk about salt: There is nothing more crushing than cutting into a gorgeously cooked braise that’s filled your home with a meltingly good aroma and finding it bland and underseasoned. I don’t want this to happen for us. As we cannot taste the inside of the meat as we go, our best bet is to actually use a correctly measured amount of salt. I estimate needing 1 teaspoon of Diamond kosher salt per pound of brisket, plus about 1/3 of that extra to account for seasoning the sauce. If the brisket is 6 pounds, I’m probably using 8 teaspoons or 22 grams of salt total. If it’s 7 pounds, 9 1/2 teaspoons or 27 grams total. Using Morton or another brand of kosher salt: 4 3/4 teaspoons total for a 6-pound brisket. Using table salt or a fine sea salt: 3 3/4 teaspoons. Does this sound highly finicky? Yes. But underseasoning makes me sad, as it’s almost impossible to correct later.
Find the right size pan: Ideally, you’ll want to use a large Dutch oven — here I’m cooking in a black 6.25-quart oval but larger would be welcome too. In the top photo, I’ve reheated about 2/3 of the total brisket in a smaller pan — this 2.25-quart casserole dish in gray. If you don’t have a large pan that can go from stove to oven, simply use your largest skillet instead and transfer to an ovenproof baking dish when you’re done on the stove. If your brisket is too big to fit across the bottom of your Dutch oven or skillet, cut it into two equal halves, as shown here.
Choosing your brisket: The “first cut” or “flat cut” brisket is the leaner, larger portion of the brisket, often resembling a thicker, larger flank steak, and is located below the fattier “point” or “second cut.” In the UK, brisket is often sold rolled, commonly referred to as “rolled brisket” or “pot roast brisket.” You should unroll it before cooking it here.
Leftovers: Will keep for up to 6 days from the day you started the braise. Reheat at 350°F (175°C) for about 30 minutes. If it ever looks low on liquid, add another 1/2 cup water.
Make this brisket in an InstantPot or electric pressure cooker: For 75 to 90 minutes on the meat/stew or “high” setting. Let the pressure naturally release for about 15 minutes.
Make this brisket in a slow-cooker: Cook it on low for 9 to 10 hours.
