While cooking your onions, garlic and celery in butter using your pressure cooker's saute function, prepare your broccoli by separating the florets from the stalk.
Set the broccoli florets aside. Chop the stalks and stems
Once your onions/garlic/celery are soft and translucent, add broccoli stems, carrots and potatoes. Season liberal with sea salt and pepper.
Add broth and cook under pressure for 5 minutes.
Use the quick depressurize method to release pressure.
Add mustard powder and potato starch to your heavy cream and mix well.
Add cream mixture, cheese and broccoli florets to your soup.
Using the warm function, allow your soup to thicken and broccoli florets to cook for roughly 5 minutes before serving. Season to taste with additional sea salt and pepper, as desired.