Combine Unsalted Chicken Stock (2 cup), Worcestershire Sauce (1 tablespoon), Light Soy Sauce (1 tablespoon), Fish Sauce (1 tablespoon) and Tomato Paste (50 milliliter) is a medium bowl.
Trim excess fat on the Whole Beef Brisket (1.5 pound). Then, generously season the beef brisket with Kosher Salt (to taste) and Ground Black Pepper (to taste).
Heat up your pressure cooker and add Olive Oil (1 tablespoon) into the pot. Sear one side of the beef brisket for roughly 5 minutes.
Sear the other side for another 5 minutes. Then, place the beef brisket on a chopping board and let the meat rest.
Add Olive Oil (1 tablespoon) to the pot, then add finely chopped Onion (2) and season with Kosher Salt (to taste) and Ground Black Pepper (to taste). Cook until the onions are tender and brown, then add crushed and chopped Garlic (3 clove) and stir until fragrant.
Add chopped Celery (2 stalk), chopped Carrot (2), and a pinch of Kosher Salt (to taste) and Ground Black Pepper (to taste), then cook for 2 minutes.
Add Sherry Wine (1 dash) to deglaze the pot, then allow the wine to reduce.
Add the chicken stock mixture to the pot.
Cut the brisket into 1 to 1 1/2 inch cubes, then toss with All-Purpose Flour (1 tablespoon).
Add the beef briskets chunks and make sure the briskets are spread out, so each piece can soak the stock mixture. Don’t stir the beef briskets as you don’t want too much flour to get into the stock mixture.
Then, add Bay Leaf (2) and rub Dried Thyme (to taste) against your fingers and sprinkle them in the pot.
Lastly, add the cubed Russet Potato (3) on top. Then, close the lid.
Electric pressure cooker: cook at high pressure for 70 minutes, then natural release.
Or use a stovetop pressure cooker: cook at high pressure for 55 minutes, then natural release.
Open the lid. Add Kosher Salt (to taste) and Ground Black Pepper (to taste) if necessary. Serve immediately with pasta, rice, or just eat it as is.