How Do You Properly Boil and Simmer? Here’s Everything You Should Know

Learning how to cook requires becoming well-versed in a multitude of important techniques. Pan-frying, kneading, proofing, dicing, and braising are all just a few of many methods that sure to lead to successful cooking. Additionally, learning how to boil and simmer properly is the key to professionally made foods like pasta, chicken stock, boiled eggs and vegetables.

Even if you don’t consider yourself an experienced cook, you likely know that boiling involves at least two things: a pot and a lot of water. Whether you plan on cooking dishes like this one-pot lemon shrimp pasta or these cream cheese mashed potatoes, you’ll need a large pot of water set over a high amount of heat. Related to boiling, but just as important, is the technique of simmering, which is how you get nicely thickened stews and softly poached eggs.

Below, we break down the basics of these common cooking techniques and teach you everything you need to know about how to execute them properly.

Boiling can most basically be described as a common cooking technique that typically involves heating a large amount of liquid, such as water, as a way of cooking ingredients such as eggs, pasta, vegetables and meats. As the liquid, or water, is heated, it will eventually reach a boiling point (212 ˚F for water) and begin to bubble rapidly and produce steam. When foods are boiled, they’re cooked while submerged in water. This is a good technique for cooking foods to different levels of doneness, such as with a boiled egg.

Simmering is a way of gently cooking ingredients in a certain amount of liquid until they are tender. It’s also a way of getting flavors in a dish to infuse and become concentrated. As a soup or a sauce simmers, herbs and spices flavor the liquid, vegetables absorb some of that seasoned liquid while also contributing some of their own flavors back — it’s synergy! Since some of the liquid evaporates while simmering and boiling, flavors are also stronger and more intense by the end of cooking.

The main difference between these techniques is the speed at which each boils. You can think of the two as a spectrum. At one end, you have a “slow simmer” and on the other end you have a “full rolling boil.” At a slow simmer, you’ll see very little movement in the liquid; wisps of steam and a tiny bubble or two every so often, but that’s it. Then you have a “simmer,” where you’ll see some gentle bubble activity. A “rapid simmer” is just below a full boil; you’ll see a lot of activity in the liquid but the bubbles will still be pretty small. When liquids are at a full, rolling boil, you’ll see big bubbles and lots of churning, frantic activity in the pot.

There are a couple reasons why it’s important to know the difference between these two methods. The temperature of the liquid is a factor (liquid at a full boil is several degrees hotter than liquid at a slow simmer), but it’s mostly about the action of those bubbles. A rolling boil causes ingredients to bump around a lot, causing them to disintegrate and also making the outsides mushy before the insides are fully cooked. At a simmer, the food is jostled just enough to move it around the pan and mix all the flavors, but not so much that the ingredients are damaged.

It’s all about controlling the heat! Liquids over high heat will boil rapidly, while liquids over a lower heat will simmer. To cook pasta, for example, you’ll need very hot boiling water with large bubbles. To thicken a chili, however, you’ll likely have to let it simmer on low covered for a while. Stovetops can be touchy, though, so you may need adjust the heat a bit to keep the liquid where you want it. Keep an eye on it — don’t totally turn your back on the pot until you’re sure the simmering is holding steady.

There’s a myth that if you add salt to almost-boiling water, it’ll raise the temperature and make it come to a full, rolling boil. While it make look like that is happening since the water bubbles furiously when the salt is added, what’s actually happening is that the salt helps form bubbles but doesn’t actually raise the temperature by any noticeable amount. The furious bubbling is only a temporary occurrence, so know that you’re salting water for flavor, not for temperature.

Bring to a boil, then reduce to a simmer: It seems counter-intuitive, doesn’t it? Why do so many recipes have you bring foods all the way up to a boil and then reduce it back to a simmer? The biggest reason is time: it can take quite a while for food to come to a simmer over medium-low heat; it’s faster to bring it to a boil, then cut the heat back. It’s also easier to control the simmer when you do it this way.

What recipes mean by boil and simmer: When a recipe says “bring to a boil,” it means a true, rolling boil. Whether you are boiling eggs or about to simmer a soup, you should see big bubbles and lots of roiling action in the pot. A recipe that tells you to “let simmer,” means you should see small bubbles merrily popping the surface, but less action and vigor than a true boil. Be aware when a recipe says to use a “slow simmer” or a “rapid simmer” and adjust the heat under the pot accordingly.

• Slow Simmer: Low heat, very little activity in the pot. You’ll see wisps of steam and a stray bubble or two, but that’s it. Most often used for stocks and braises.
• Simmer: Medium-low heat, gentle bubbling in the pot. Most often used for soups, sauces, and braises.
• Rapid Simmer: Medium- to medium-high heat, more aggressive bubbling in the pot, but the bubbles should still be fairly small. Most often used for reducing sauces.
• Boiling: High heat, lots of big bubbles over the whole surface of the liquid, roiling activity in the pot. Most often used for boiling pasta and blanching vegetables.

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