Which cooking method uses steam to cook food inside a closed container?

The cooking method that uses steam to cook food inside a closed container is steaming. This technique involves placing food in a steamer basket or on a rack above boiling water, which generates steam that surrounds and cooks the food. The steam retains moisture, helps preserve nutrients, and often contributes to a tender texture without the use of added fats.

In contrast, boiling immerses food directly in water, which is not the same as using the steam produced in a closed environment. Grilling is an outdoor cooking method that uses direct heat and does not involve steam as a cooking medium. Braising combines moist and dry heat, often starting with browning the food and then cooking it slowly in a small amount of liquid, but it does not focus on steam as the primary cooking method. Therefore, steaming is clearly defined by the use of steam within a closed space, making it the correct answer.