Season the chuck roast all over with the salt, pepper, and Cajun seasoning.
Brown the mushrooms
Set the Instant Pot to SAUTE on high. Wait 5 minutes for it to heat up.
Add the oil (see Notes), and wait for the oil to heat. You can tell when it is ready because you'll see little ripples in the surface.
Add the mushrooms and saute until browned (~10 minutes), stirring every minute or so.
Transfer the mushrooms to a plate and set aside.
Sear the roast
With the Instant Pot still set on high for SAUTE, add the roast. (see Notes). Push the roast down gently with a utensil to ensure good surface contact with the pot.
Sear 5 minutes per side. Transfer to a plate or cutting board.
Make Instant Pot pot roast
To the Instant Pot still set on high for SAUTE, add the garlic and beer. Using a wooden spatula or spoon, scrape all the little seared bits and yum yums from the bottom of the pot.
Add back the roast. Add the mushrooms, minced onion, Worcestershire sauce, and tomatoes.
Put on the Instant Pot lid and secure with the pressure release valve set to SEALING.
Set Instant Pot to cook MEAT/STEW, pressure level HIGH, for 60 minutes.
Once cycle is complete, allow to IP vent naturally (meaning, don't touch it) for 10 minutes.
Release the remaining pressure (use a dish towel to protect your hand because some steam will still come out) by switching the pressure release valve to VENTING. Open pot.
Finish the sauce
Set the Instant Pot to SAUTE on high again.
In a small bowl, combine the cornstarch and 2 tablespoons cold water. Add to the pot.
Let the sauce simmer a minute, then turn it off.
At this point, the meat is too hot to heat (I learned the hard way), so let it set ~15 minutes to cool a bit and allow the cornstarch to do its thing and thicken the sauce.
Break the meat up into bite-sized pieces. Serve over noodles, rice, potatoes, grits, or just enjoy as is.
Notes
If your Cajun seasoning does not include salt, increase kosher salt amount to 2 teaspoons.If your roast is too large to fit in the pan (I used a 2-1/2 pounder for these photos), you can cut it in two and sear them sequentially.To make this in the oven or slow cooker, see above in the reading for directions.
Nutrition
Calories: 699kcal (35%)
Calorie count is purely an estimate calculated using an online application to serve as a guide and not to be taken as accurate nutritional information. Percent Daily Values are based on a 2,000 calorie diet.
Keyword cajun pot roast, instant pot beef recipes, instant pot pot roast, pressure cooker pot roast
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