The boiling point of water is 212 degrees F, but what does that mean?
At that temperature, water turns from liquid to vapor. In the gaseous form, water is called steam. Like any other gas, steam is invisible.
“But,” you say, “I can see the steam coming out of the teapot when it’s boiling!”
Not so! What you are seeing is the water vapor or tiny droplets that form as the steam condenses with it contacts the cooler outside air.
You are here to learn to make the best tasting food you’ve ever eaten, not sit through a boring science lesson. But just hang on, it will all come together in a minute.
In steam cooking, the steam conducts the heat to the food. This provides big advantages. First, the process delivers even heat. It cannot be hotter than 212 degrees F (unless it’s contained as in a pressure cooker) and it cannot be cooler than 212 degrees F because then it condenses back into liquid water.
In steam cooking, food items are often suspended above the boiling liquid. For example, the steam baked potatoes in a Dutch oven, you put 1/2-3/4 inch of water into the bottom of the oven, space four, clean 1-inch diameter stones in the oven, and place a heat-safe plate or grate on top of the stones. Set your big Idaho Russet potatoes on a plate, cover the Dutch oven, and put in on the fire. After about 20 minutes, begin checking the potatoes for doneness and make sure you keep some liquid in the bottom, but not contacting the potatoes. When the blade of your pocket knife slides easily through the center of the largest potato, they are done…and you are in for a treat.
French chefs use another method of steam cooking called “en Papillote” which translates to “in Paper” or “in foil.” Outdoor cooks call them “foil packets” or “hobo dinners”. All you are doing is sealing the food in a packet, then heating it so it steams in its own juices.
The big difference between steam cooking and boiling is the steaming (the food has little or no contact with the liquid water). This is a good thing for several reasons. First, there is no agitation. In boiling, the food is bounced around by the bubbles and can change texture. Second, some foods will absorb water when simmered. They become water-logged (think mushy broccoli and cauliflower). Finally, submersion in water for any length of time tends to leach both nutrients and natural, vibrant colors out of food. Steaming does not.