This answer used to frustrate me to no end until I realized that my bosses weren’t testing me, but rather encouraging me to pay attention to the sensory cues that signified that a desired change had taken place.
“Heat is the element of transformation,” Samin Nosrat writes in one of my most frequently referenced cookbooks, Salt Fat Acid Heat, and I’m here to tell you that there are few tools more streamlined in applying heat than the microwave.
There are very few meals I make that don’t involve a microwave at some point in the process. Leveraging the microwave’s magic can expedite just about any meal.
“Par-boiling” potatoes before roasting them in a hot convection oven can be done in under 5 minutes without having to worry about bringing water to a boil and dirtying a colander. Perfectly “blanched” asparagus for a refreshing spring salad can be done in 2 minutes without hassling with a steaming basket or an ice bath. “Pressed” tofu for stir-fry dishes can be done in minutes, rather than hours. Confit garlic, tempered chocolate, and poached chicken - all accomplished in a matter of seconds and with minimal cleanup.
At the most basic level, to cook is to change the chemical structure of food with thermal energy (you can also make these changes with salt or acid, but that’s a different conversation for a different day) and there are three primary ways that a cook can catalyze this energy transfer.
A second method is convection, which is when heat energy is transferred via a fluid e.g. pasta in submerged boiling water, a french fry bubbling in hot oil, or the warm air circulating around a roast chicken. Pro-tip: You should be using the convection setting on your oven, if you have one!
In each of these cases, heat energy is transferred to the surface of a food through the cookware or surrounding environment, and that energy eventually makes its way to the center of the food, cooking it from the outside in.
A third form of heat energy comes from electromagnetic radiation. Inside the chamber of a microwave, electromagnetic microwave rays bounce around, causing the water molecules inside a food to move around until they have enough energy to evaporate, essentially steaming food from the inside out. Because microwave rays heat food directly, microwave cooking is undoubtedly the most efficient method of heat transfer.
In fact, many nutrients, especially water-soluble vitamins and minerals that would otherwise be lost to a cooking liquid and thus, poured down the drain, are often better retained through microwave cooking.
Furthermore, because microwaves reach temperatures high enough to kill off any harmful pathogens, and because you are less likely to handle food while it rotates in a sealed box, microwave cooking is actually a great way to minimize food safety concerns and prevent cross-contamination.
Here are a few tips and tricks that will help you get the most out of your microwave.
Remember that microwaves are incredibly efficient and can turn food from perfectly moist to dry and leathery in a matter of seconds. Working in small time increments and checking or stirring your food often will prevent overcooking. It’s also important to remember that microwaves are drawn to the densest areas of a food. Spreading ingredients evenly across a container or stirring thick soups and stews throughout the cooking process will ensure even heating.
The power settings on a microwave refer to how much electrical energy is converted to electromagnetic energy. High moisture foods like soups, fish and vegetables work well on high power settings because there is an ample amount of water to convert energy to heat quickly. Denser foods like meat and grains should be heated at a lower setting, anywhere from 50-70%, to allow the food to heat at a slower rate without drying out. Low settings below 50% are best for melting ice, softening butter, and tempering chocolate.
Microwaves work by exciting water molecules in whatever food you are heating, but they will not add moisture. Placing a small glass of water next to, or in the center of whatever you are cooking will help prevent food from drying out. Whenever I microwave leftover rice, I always place a damp paper towel over it to add steam.
Always double check to make sure that your containers are microwave safe. While the electromagnetic radiation itself doesn’t pose a threat to your food, it can cause certain plastics to degrade and impart off-flavors and potentially hazardous chemical compounds into a dish.
There are some things that a microwave just can’t do. Caramelization and the complex flavors of the Maillard reaction won’t occur in a microwave, nor will you ever achieve the satisfying crunch that results from frying in hot oil. It is important to remember that like any piece of cooking tech, a microwave is a useful tool, but it won’t do all the work for you.
But when used thoughtfully as one step in a larger process, there is no tool that I rely on more (other than my knife, of course).