Steam

Steaming is a moist-heat cooking method in which food is cooked by hot water vapour. The food is usually placed above boiling water in a steamer basket, perforated tray or combi oven, allowing steam to transfer heat without the ingredient being immersed in the liquid. Steaming is used for vegetables, fish, dumplings, shellfish, rice and many other foods.

How steaming works

Water is heated until it produces steam, which transfers heat to the food as it condenses on the cooler surface. At normal atmospheric pressure, saturated steam is approximately 100°C at sea level; pressure-steaming equipment can operate at higher temperatures. Cooking time depends on the food’s size, thickness, starting temperature and the equipment.

Common steaming methods

• Basket steaming: food sits above simmering or boiling water in a covered pot.
• Commercial steamer: a dedicated appliance supplies controlled steam to trays of food.
• Combi oven: steam or a combination of steam and hot air is used to cook food.
• En papillote: food is enclosed in a parcel and cooks in its own moisture and added liquid; this is related to steaming but uses a different setup.

Steaming versus boiling

Steaming cooks food through hot vapour above the water. Boiling cooks food immersed in liquid. Steaming can reduce leaching of water-soluble nutrients into cooking water, but the nutritional result depends on the food and cooking time.

Chef’s tip: Arrange food in a single layer where possible and avoid overcrowding the steamer. Use a tight-fitting lid or suitable equipment to maintain consistent steam and check doneness in the thickest part.

Key distinction: Steaming uses hot water vapour to cook food; it is not the same as boiling or poaching in liquid.