Add 1 cup water in the instant pot steel insert. Place trivet and place potatoes on top of the trivet. Close lid with vent in sealing position. Pressure cook on Steam mode at high pressure for 10 mins. (see notes for cooking time variation) When the instant pot beeps, let the pressure release naturally.

Brush the potatoes with half the fat. Arrange the potatoes in a baking dish. Brush the potatoes all over with 2 tablespoons of butter or other fat, including the bottoms. Season with salt and pepper. Sprinkle the potatoes generously with salt and pepper. Bake 30 minutes, then brush with more fat.