2 tablespoons vegetable oil
2 pounds beef stew meat, cut into 1 ½-inch pieces
Kosher salt
Freshly ground black pepper
¼ cup all-purpose flour
1 yellow onion, cut into wedges
8 ounces cremini or button mushrooms, halved if large
3 garlic cloves, minced
2 (12-ounce) bottles stout beer (such as Guinness)
1 cup beef broth
2 tablespoons Worcestershire sauce
1 teaspoon whole-grain mustard
2 sprigs fresh thyme
1 bay leaf
4 carrots, peeled and cut into 1-inch rounds
6 red potatoes, quartered
Heat the oil in the Instant Pot using the sauté function.
Season the meat generously with salt and pepper and then toss it with the flour to coat.
Add the meat to the pot. Cook, stirring occasionally, until the meat is browned on all sides, about 5 minutes. Remove the meat from the pot.
Add the onion and mushrooms to the pot and cook, stirring, until softened, about 5 minutes.
Stir in the garlic and then add the beer, broth, Worcestershire sauce, mustard, thyme, bay leaf, carrots, and potatoes. Return the meat to the pot and stir to mix.
Close the lid of the pot and turn the valve to the sealing position. Choose high pressure and set the timer for 40 minutes.
When the cooking time is up, let the pressure release naturally for 10 minutes and then quick release any remaining pressure.
Serve hot.