Step 1

Take the brisket and cut it in half against the grain so it fits into your Instant Pot. Rub the brisket all over with kosher salt.

Step 2

On the Instant Pot, hit Sauté and Adjust so it’s on the More or High setting. Once it says Hot, working with one piece at a time, sear the brisket for 2 minutes on each side, or until browned. When done, hit Keep Warm/Cancel, move the brisket to a plate, and clean and dry the liner pot.

Step 3

Make the sauce by whisking together the water, ketchup, brown sugar, vinegar, and garlic in a mixing bowl.

Step 4

With the liner pot and the trivet in the Instant Pot, place one half of the brisket on top of the trivet, fat-side up, and cover with about half of the onions and sauce. Then, in crisscross fashion, layer the other half of the brisket (also fat-side up) on top of the onions. Cover the brisket with the remaining onions and sauce.

Step 5

Secure the lid, move the valve to the sealing position, and hit Manual or Pressure Cook on High Pressure for 75 minutes if you want it super tender (shredding apart) or 65 minutes if you want it a little firmer. When done, allow a 20-minute natural release followed by a quick release.

Step 6

Very carefully transfer the brisket halves to a carving board (placing them fat side up) and let cool for 15 minutes. If you decide to carve it up into strips right away before it’s done cooling, it will shred apart. While you wait, you may carefully shave off any undesired fat and discard (or keep it on if you wish).

Step 7

Meanwhile, as the brisket’s cooling, mix the cornstarch with 3 tablespoons cold water to form a slurry and set aside.

Step 8

Hit Keep Warm/Cancel and then Sauté and Adjust to the High or More setting to bring the sauce to a simmer. Add the slurry, stir immediately, and allow it to simmer for 30 seconds before turning the pot to the Keep Warm setting. The sauce will thicken as the brisket cools.

Step 9

Once the brisket has cooled, use a carving knife to cut it into strips or chunks, slicing against the grain (meaning the opposite direction that the strings of meat are going in).

Step 10

Carefully return the slices of meat to the Instant Pot and allow to marinate in the sauce (on the Keep Warm setting) for 5–10 minutes, so it stays tender until ready to serve.