When using it as an oven use a metal baking tray, non-stick if you prefer. When using it as a grill, also use a metal baking tray, but don't use non-stick, as the direct grill heat can damage the non-stick surface. For microwave cooking, you can use anything designed for microwave cookers, including ceramic plates labelled 'safe for microwave use'. There should be no metal present when using it as a microwave.