Cooking aromatics gently in fat until they soften and release their moisture, deliberately without letting them colour.
Technique at a glance
A compact visual model of the lesson. Use the full mechanism and success criteria below when you practice.
Concept
Cooking aromatics gently in fat until they soften and release their moisture, deliberately without letting them colour.
What changes
Sweating and sautéing use the same pan and differ only in temperature and intent.
What good looks like
Onions go from opaque white to translucent with no gold at the edges — that transition is the entire endpoint.
Practice counts when you cook
Reading this brief does not change your School state. Finish a real practice dish in Cook mode and log the cook; that cook is the evidence that advances the skill.
What to focus on
Mechanism
Sweating and sautéing use the same pan and differ only in temperature and intent. Below browning temperature, an onion's cell walls break down and it releases water and turns translucent; its harsh sulphur compounds volatilise off and its sugars stay unbrowned, so what you get is sweetness and depth without any roasted note. That distinction matters because browned onion tastes of browned onion — assertive and slightly bitter — and there are dishes where that would dominate everything else. A béchamel, a risotto base, a pale soup all want the aromatic foundation and none of the colour. The released moisture is also doing work: it keeps the pan temperature at or below 100°C on its own, which is why a lid or a pinch of salt makes sweating more reliable than watching the heat.
Success criteria
Onions go from opaque white to translucent with no gold at the edges — that transition is the entire endpoint.
There is a gentle, wet sizzle rather than a hard one, and visible moisture in the pan.
They smell sweet and mild rather than sharp, which means the volatile sulphur compounds have gone.
A piece squashes against the side of the pan with no resistance.
Failure guards
The onions browned.
Heat too high, or too little fat. Once they colour they cannot be uncoloured, and the dish will taste of it.
They are still crunchy after ten minutes.
Heat too low, or too many in the pan. Sweating is gentle, not cold — it should be actively cooking.
The finished sauce has a raw vegetal edge.
Not sweated long enough. Ten minutes is not padding; undercooked aromatics leave a background note that nothing added later covers.