To make the marinade you will need to combine maple syrup, balsamic vinegar and soy sauce.
Season pork roast with salt and pepper. Rub garlic on top of roast and pour in marinade. Let pork marinate in fridge for at least 2 hours.
Open the lid, place onion on bottom to prevent pork roast from sticking.
Now put your pork roast on top.
Add the liquid (vegetable stock).
Place apple slices on top of the pork roast.
Close the lid. Set manual, high pressure cooking, for 20 minutes.
When done, let the pressure release naturally (about 10 minutes).