Press the Sauté key on the Instant Pot (it should say Normal, 30 mins). Add coconut oil and once hot, add the onion and salt and cook for 2 minutes, stirring a few times.Add the beef strips and stir together for 2 minutes, until the colour of the meat changes.Add the mushrooms, garlic, tomato paste, mustard, bay leaf and beef stock and stir through to combine. Cancel the Sauté function by pressing Keep Warm/Cancel button.Place and lock the lid, make sure the steam releasing handle is pointing to Sealing. Press Manual (High Pressure) and adjust to 10 minutes. After 3 beeps the pressure cooker will start going.Once the timer goes off, allow the pressure to release for 2-3 minutes and then use the quick release method before opening the lid.Press Sauté key again. Scoop some of the stew liquid into a small cup and dissolve the tapioca flour in it (or other starch that you're using). Add back to the stew and stir through, which will thicken the liquid slightly. Add the sour cream/crème fraîche and peas and stir through for a minute.Finally add the parsley, stir and serve with potatoes, rice or pasta, or over some steamed vegetables.