Step 1

Place the roast in the Instant Pot.

Step 2

In a blender, combine the diced onions, tomato paste, Worcestershire sauce, rosemary, thyme, salt, pepper, and broth. Blend until smooth. Pour the sauce over the roast.

Step 3

Secure the lid on the pot. Close the pressure-release valve. Select MANUAL and set the pot at HIGH pressure for 15 minutes. At the end of the cooking time, use a quick release to depressurize.

Step 4

Open the lid, and stir in the carrots, pearl onions, potatoes, celery, and mushrooms. Secure the lid on the pot. Close the pressure-release valve. Select MANUAL and set the pot at HIGH pressure for 4 minutes. At the end of the cooking time, allow the pot to sit undisturbed for 10 minutes, then release any remaining pressure.

Step 5

Carefully transfer the roast to a bowl and coarsely shred it, then transfer onto a serving platter. Arrange the vegetables around the meat.

Step 6

Serve the pot liquid as a sauce on the side.