Brown Chuck Roast Steak: Heat up Instant Pot by using “Sauté More” function. Wait until Instant Pot says “HOT”. Pat dry chuck roast, season one side of beef generously with salt and ground black pepper. Drizzle 1 tbsp (15ml) olive oil in Instant Pot. Ensure the oil is coating the whole bottom of the pot. Carefully place seasoned side of chuck steak in Instant Pot. Generously season the other side with salt and ground black pepper.Brown one side of the beef for 7 minutes before flipping over, then brown the other side for another 7 minutes. Set aside browned beef in a large container.
Make Umami Chicken Stock Mixture: While chuck steak is browning in Instant Pot, mix 1 tbsp (15ml) Worcestershire sauce, 1 tbsp (15ml) regular soy sauce, 1 tbsp (15ml) fish sauce, 1 tbsp (16g) tomato paste with ½ cup (125ml) unsalted chicken stock.
Sauté Vegetables: Add 1 tbsp (15ml) of olive oil in Instant Pot if necessary. Add sliced onions & shallots, then sauté until soften (~1 min). Add minced garlic cloves, then stir for roughly 30 secs until fragrant. Add quartered mushrooms, then sauté for another 3 mins. Season with salt and ground black pepper if desired.
Deglaze: Pour in ½ cup (125ml) Guinness draught and completely deglaze the bottom of the pot by scrubbing the flavorful brown bits with wooden spoon. Pour in remaining ½ cup (125ml) Guinness draught.
Pressure Cook Vegetables: Add 1 bay leaf, 2 sprigs thyme, 1 sprig rosemary, 12g 70% dark chocolate, russet potato chunks, carrot chunks and chicken stock mixture in the pot. Mix well. Close lid and pressure cook at High Pressure for 4 minutes and Quick Release. Open the lid carefully.
Cut Chuck Steak: While the vegetables are pressure cooking, cut chuck steak into 1.5 to 2 inches thick cubes. Place all cubed beef and meat juice back in the large mixing bowl. Add 1.5 tbsp (12g) flour in mixing bowl and mix well with the beef.
Pressure Cook Irish Stew & Yukon Gold Potatoes: Set aside half of the carrot chunks & all mushrooms from Instant Pot. Place cubed beef and all its juice in Instant Pot. Partially submerge the beef in the liquid without stirring, because you don’t want too much flour in the liquid. Layer a stainless-steel bowl filled with halved Yukon gold potatoes on top. Close lid, then turn Venting Knob to Sealing position. Pressure Cook at High Pressure for 32 minutes, then Natural Release for 10 minutes. Open the lid. Set aside the stainless bowl. Thicken Stew and Add Vegetables: Discard bay leaf and the herbs. Press Sauté button. Breakdown the mushy russet potatoes with wooden spoon. Stir to thicken the stew. Add sautéed mushrooms, and the previously set aside carrots in the pot. Taste and season with salt and ground black pepper if necessary.
Make Mashed Potatoes: Drain and transfer Yukon gold potatoes to a larger mixing bowl. Mash the potatoes with a potato masher. Mix in 100ml whole milk and 1 to 2 tbsp (14g - 28g) unsalted butter. Season to taste with salt & pepper.
Serve: Garnish with Italian Parsley. Serve Irish stew and mashed potatoes. Enjoy~