Press the 'SAUTE' button, set it to 'NORMAL' and wait until it displays 'HOT'. Add a tablespoon of oil, once it heats up, add half of the beef cubes in a single layer, cook until browned on all sides, stirring frequently. Transfer the meat to a plate. Repeat with the remaining batch of meat, adding a tablespoon more of oil if necessary.

Add sliced mushrooms, saute for 2-3 minutes, scraping the bottom of the pot as you saute. The mushrooms will release moisture which will help pick up all the brown bits (known as fond) at the bottom of the pot. Transfer the mushrooms to a plate and set aside.

Add diced onions, carrots, and celery, cook for 2-3 minutes while stirring occasionally. Add more oil if required to saute the veggies.

Next, add minced garlic, cook until fragrant, another 30 seconds.

Add the tomato paste and seasoning mix. Cook for 2 minutes. At this point, if you still find some browned bits stuck at the bottom of the pot (ideally you shouldn't), use ¼ cup of the beef stock to de-glaze the pot in order to avoid any potential 'BURN' error. Press 'CANCEL' to turn off the saute mode.

Add the rinsed barley, browned meat along with its juices and sauteed mushrooms to the pot.

Next, add the stock and water.

Add Worcestershire sauce, give everything a really good mix.

Throw in the bay leaves.

Close the lid of the Instant Pot with the valve on 'SEALING' position. Press the manual or pressure cook button and pressure cook on high for 20 minutes. It will take some time for the pressure to build up (about 22 minutes), after which the timer will start.

Once the cooking cycle is complete, let the pressure release naturally for 10 minutes, then do a quick release following the manufacturer's instructions. Once the float valve (silver pin) drops, open the lid.

Sprinkle chopped parsley, and mix well. Check for seasonings and adjust accordingly. Discard the bay leaves before serving.

Dish out, sprinkle some parmesan cheese if desired. Enjoy your very own homemade beef barley soup along with some crusty bread.