Prep all your ingredients.
In a fry pan on high or in your pressure cooker on the saute function, add 1 tbsp of oil and half of the chuck steak. Sprinkle 1/4 tsp of salt and pepper over the meat and seal until the meat is brown. Repeat with the remaining half.
Once the meat is done remove and leave to rest.
Turn down the heat to medium and add unsalted butter, onions and mushrooms. Saute until soft.
Add the stock, sugar, thyme, Worcestershire sauce and a good pinch of salt. Combine and deglaze the pan.
Put the meat, mushrooms and stock into the pressure cooker and set it to high / meat setting and cook for 35 - 40 mins.
Prepare you rice / egg noodles / pasta according to the packaging.
In a small bowl, combine the cornstarch with water and stir until smooth.
After 35 minutes, release the pressure valve in accordance to your user pressure cooker manual guidelines.
Carefully open the pressure cooker and check the consistency of your meat. If you like it softer then cook it longer. Also, if you want a clearer and lighter stroganoff, skim the fat and scum off the surface.
Add the sour cream, dijon mustard and cornstarch mixture (give the cornstarch a quick stir if it has separated). Combine gently with a wooden spoon.
Taste check for seasoning (salt and pepper), thickness (cornstarch mixture) and creaminess (sour cream). Adjust according to your preferences.
Serve with rice / egg noodles / pasta and garnish with chopped parsley.