Simmer

A boil is vigorous: large bubbles, lots of movement and rapid evaporation. A simmer is calmer: small bubbles, a steady heat and less agitation. That difference shows up quickly in the pot. At a boil, pasta and some vegetables cook fast but can knock into each other and fray; at a simmer, dumplings, fish, meatballs or stuffed pasta are less likely to break.

Simmering is also a common instruction for soups and stews because it keeps the liquid clearer and the surface calmer, so fats and impurities are easier to skim if the recipe calls for it. When a recipe wants reduction and concentration, it may ask for a brisk simmer or an uncovered simmer rather than a full rolling boil.

Simmering is a controlled way to move heat into the centre of food. For collagen-rich meats, a long, steady simmer gradually softens connective tissue, giving a tender result without the shredding that can happen with more violent bubbling. For legumes and grains, simmering helps them hydrate and cook through evenly; too much agitation can break skins and make the pot starchy.

For sauces, simmering is often about gentle thickening. Starches swell and sauces reduce without scorching as easily as they might at higher heat, though you still need to stir if the base is thick. For eggs, custards and dairy-based mixtures, a bare simmer can prevent curdling that a boil would trigger.

Some recipes want a bare simmer, just a few bubbles, because the ingredients are fragile or the liquid should stay clear. Think poached chicken for shredding, fish in broth, or a delicate consommé-style soup. Others call for a lively simmer because the goal is reduction: tomato sauces, braising liquids that need to concentrate, or stocks that should gently bubble for hours.

Also notice whether the recipe simmers covered or uncovered. A lid traps heat and limits evaporation, which suits grains, pulses and dishes where you want a brothy finish. Uncovered simmering reduces and intensifies, but it also demands a little more attention to prevent sticking as the pot thickens.

On most hobs, the easiest way to hold a simmer is to bring the pot up to a boil first, then immediately reduce the heat until the surface calms. A wide pot evaporates faster than a tall narrow one, so the same heat setting can behave differently depending on the pan.

If you are simmering something that tends to foam, such as some pulses, keep the heat low enough that the foam does not climb, and give the pot enough headroom. For thick soups and sauces, a simmer can happen underneath the surface before you see bubbles; listen for a gentle blip and stir to check the bottom is not catching.

Simmering can mean anything from a quick sauce to an all-afternoon pot, so Cooking time is a useful companion when you are comparing recipes. Difficulty can also help: some simmered dishes are straightforward once the pot is set, while others involve careful skimming, staged additions or finishing steps that ask for more attention.