Make breadcrumbs.

Mash the fish, breadcrumbs and warm milk together.

Stir the yolks, salt and pepper into the fish mixture.

Whisk the egg whites until stiff.

Gently fold into the fish mixture using a metal spoon.

Pour the mixture into a greased, ovenproof soufflé dish. Cover with foil and tie securely with string.

Put the dish in the basket.
Place the trivet in the pan and pour in 1 1/4 pint (750ml) water.
Lower the basket onto the trivet.

Close the lid and bring to full pressure.

Cook for 12 minutes. Release steam quickly.