Simmer

A simmer is liquid kept just below boiling, with small, gentle bubbles rising to the surface. It cooks soups, stews and sauces without toughening them.

Also called Simmering, Simmered, Gentle simmer.

To simmer is to cook food in liquid that is hot enough to bubble gently, but not at a full boil. Small bubbles rise steadily and break the surface, and the liquid moves only a little. At sea level a simmer is roughly 85 to 96°C (185 to 205°F). Soups, stocks, stews, sauces, beans and grains are usually simmered.

How to do it

Bring the liquid to a boil over high heat. This is faster than heating slowly.
Turn the heat down until the big, rolling bubbles calm to small, steady ones.
Adjust as you go. A pot that is covered, or that just had cold food added, will change speed.
Cover, partially cover or leave uncovered as the recipe asks. Uncovered, the liquid will reduce.
Stir now and then, scraping the bottom, so thick liquids do not catch.

How to tell it is done

You can judge the heat by the bubbles:

Gentle or low simmer: a few small bubbles break the surface every second or two, mostly at the edges. Used for stocks, braises and delicate sauces.
Simmer: small bubbles rise steadily across the surface. Used for soups, tomato sauce and beans.
Brisk simmer: many small bubbles, but the surface is not churning. Used for reducing a sauce.

If large bubbles are breaking hard all over, it is a rolling boil. If the surface barely shivers, you are close to a poach.

Why it works

A simmer is hot enough to cook food through and melt the connective tissue in meat, but gentle enough that proteins do not seize and turn tough. It also keeps stocks clear, because the liquid does not churn fat and particles back into it.

Common mistakes

Letting it boil. Meat in a stew gets dry and stringy, and stock goes cloudy.
Judging by the dial. Every stove and pot is different. Watch the bubbles.
A lid that turns a simmer into a boil. Check the pot a few minutes after you cover it.
Not stirring thick sauces. They burn on the bottom even at a simmer.

In recipes

"Bring to a boil, then reduce to a simmer" is the most common instruction. "Simmer until tender" means keep it going, checking every 10 to 15 minutes.