Using a steel vessel for baking in a microwave oven is not recommended. Steel is a conductive material, and it can cause the microwave to reflect or bounce off the walls of the oven, which can result in uneven cooking and potentially damage the appliance.
Microwave ovens work by emitting microwaves that are absorbed by the food, causing the water molecules in the food to vibrate and generate heat. The microwaves pass through most glass, ceramic, and microwave-safe plastic containers, allowing the food to cook evenly.
If you want to bake in a microwave oven, it's best to use microwave-safe cookware such as glass, ceramic, or microwave-safe plastic containers specifically designed for microwave use. These materials allow the microwaves to pass through and heat the food effectively.
If you don't have suitable microwave-safe cookware for baking, it's recommended to use a conventional oven for baking purposes. Conventional ovens use radiant heat from heating elements to cook food, making them more suitable for baking with metal or steel pans.