Generously season the chuck roast with salt and pepper. Set it aside.
Heat olive oil in an Instant Pot on saute mode until smoking. Then, add the chuck roast to brown. Sear each side for 2-3 minutes to create a nice crust. Set the roast aside.
Warm butter in saute mode and add the onion, carrots, and celery. Cook until the onions become translucent and soften, then add the garlic cloves and cook for another minute.
Stir in the tomato paste, marmite, and Worcestershire sauce and cook for 30 seconds until they become aromatic.
Deglaze with water and Better than Bouillon, scraping up the brown bits left by the meat.
Nestle the beef into the pot and add the bay leaves, thyme springs, and potatoes. Secure the lid, and set the Instant Pot to manual high pressure. Allow the meat to cook for 1 hour with a 10-minute natural release.
Unplug the Instant Pot and stir in the fish sauce.
Notes
Expert Tips:
Select boneless beef chuck with a good amount of marbling.
Sear the beef to lock in moisture and build the base of flavor for the roast.
Cut the vegetables the same size to ensure they cook at the same rate.
Deglaze the Instant Pot with water and Better Than Bouillon, scraping up the burnt bits at the bottom to avoid a burn notification.
Nutrition Disclosure:
The nutritional information shown is an estimate provided by an online nutrition calculator. It should not be considered a substitute for professional advice.