Prepare Pressure Cooker: Heat up your pressure cooker over medium high heat (Instant Pot: press Sauté button and click Adjust button to go to Sauté More function). Make sure your pot is as hot as it can be (Instant Pot: wait until the indicator says HOT).
Prep Ingredients: While the pressure cooker is heating up, you can prepare the ingredients as indicated. You should have about 24 mins including the time for browning the chuck steak.
Brown Chuck Steak: Season one side of the chuck steak generously with kosher salt and freshly ground black pepper. Add 1 tbsp (15ml) peanut oil in pressure cooker. Ensure to coat the oil over whole bottom of the pot. Carefully place the seasoned side of chuck steak in pressure cooker. Generously season the other side with kosher salt and freshly ground black pepper. Brown for 7 mins on each side without flipping. Remove and set aside on a chopping board.
Make Chicken Stock Mixture: While the chuck steak is browning in pressure cooker, mix 1 tbsp (15ml) light soy sauce, 1 tsp (5ml) dark soy sauce, 3 drops of sesame oil, 2 tbsp (28g) brown sugar, and ½ cup (125ml) unsalted chicken stock in a glass measuring cup.
Sauté Onion & Garlic: Add sliced onion (227g) and shallot (50g) to the pressure cooker. Sauté for roughly 2 mins. Add in minced garlic cloves, ginger, and 6 dried Chinese red chili (optional), stir for roughly 90 seconds until fragrant. Do not let the garlic burn.
Deglaze: Pour in the soy sauce chicken stock mixture (from Step 4) and completely deglaze bottom of the pot by scrubbing the flavorful brown bits with wooden spoon. Turn off the heat briefly to cut the chuck steak.
Cut Chuck Steak: After deglazing, cut the chuck steak into ⅛ inch thick beef slices. Since chuck roast grains run in different directions, slice it against the grains the best you can. Place beef slices and the flavorful meat juice in pressure cooker. Make sure all beef slices are partially submerged into the cooking liquid.
Pressure Cook Beef Slices: Close lid and pressure cook at High Pressure for 12 minutes + 12 minutes Natural Release (after the pressure cooker has finished cooking, wait 12 minutes then carefully release the remaining pressure). Turn off the heat. Open the lid carefully.
Thicken Sauce: Press Cancel button and Sauté button to heat up the sauce. In a small mixing bowl, mix cornstarch with water and mix it in one third at a time until desired thickness. Add green onion strips and give it a few quick stir. Taste and adjust the seasoning with kosher salt and brown sugar if necessary.
Serve: Serve Mongolian Beef with Jasmine rice and other main & side dishes. Serve immediately.