The principal ingredient of that recipe is mustard. There are going to be 3 different types of mustard mixed with the meat. The sauce should be really well flavored.
Put the instant pot in browning mode
Brown the roast on all sides
Add the onion
Brown 2min more
Add all the other ingredients
Switch the instant pot to pressure cooking mode 24min
Serve with potatoes sprinkled with sauce
Servings 2