Press the sauté button, add the oil and hot sausage to the pot and cook until mostly browned, then add onion and pepperoni and stir-fry for another minute.
Add the remaining ingredients to the pot (except for the toppings).
Secure the lid, close the pressure valve and cook for 5 minutes at high pressure.
Naturally release pressure (or wait 10 minutes, then release remaining pressure).
Garnish with cheese and parsley.