Pressure Cooker Irish Stew

lamb shoulder chops (whole, halved or cut into cubes., 2.5 - 3.5lbs)

olive oil

large onions (peeled and sliced into thin rounds)

large carrots (peeled and cut into large chunks)

waxy baby potatoes (cut in half)

Salt and pepper

water (500ml)

sprig thyme

arrowroot or cornstarch (to thicken, if desired.)

freshly chopped parsley, or chives