How to sweat onions? (3 steps how)

In this article, we will answer the question “How to sweat onions?”, and how to store onions?

How to sweat onions?


  • Onions (sliced, diced, or rings)
  • Oil or butter 


Follow the steps below to sweat onions.

  1. In a saucepan, melt some oil or butter. Add onions and cover them with a dampened cartouche. Cover the saucepan with a tight lid and let the onions sweat on low heat.
  1. Check the onions If you see too much steam escaping the pan. When the cartouche becomes dry, re-dampen it. In case the onions at the bottom are browned, do not stir it in the rest of the onions. Your best bet is to start over.
  1. Onions will be done after 10-15 minutes of sweating. They should be perfectly translucent. The onions should be easily smashed between your fingers and should have a mild and sweet taste.

How to store onions?

Follow the guidelines below for the safe storage of onions and to extend their shelf-life.

  1. Like shallots and garlic, onions should be stored in a cool, dry, and dark place away from heat sources like sunlight and stovetop. The pantry or kitchen cabinet works fine.
  1. Do not wash the onions beforehand. 
  1. Do not keep the onions in a pile. The onions at the base of the pile will go bad quickly.
  1. Keep the onions in a ventilated paper bag and leave it open. If you are using a bowl or container, do not cover it and let the onions breathe. Do not use a plastic bag for storing onions. It will block air circulation.
  1. Keep the onions away from ethylene-producing fruits and vegetables like apples, bananas, and tomatoes.
  1. Sliced, cut, or chopped onions should be kept in an air-tight container or freezer bag to seal the moisture and the pungent smell of onions.
  1. Cooked onions should be placed in an air-tight container or freezer bag and stored in the fridge. 

The shelf-life of onions

In the pantryIn the fridgeIn the freezer
Whole onions1-6 monthsNot recommendedNot recommended
Half-cut onionsNot recommended6-10 daysNot recommended
Chopped or sliced onionsNot recommended6-10 days6-8 months

How to buy onions?

When shopping for yellow and red onions, look for the ones with dry and peppery skin. They should have a firm texture and a considerable weight that shows they are not overripe. The onions should not have soft or mushy areas.

When shopping for spring onions, look for the ones with unbruised and frim stalks. The bulb should not be slimy. Leeks should have crisp and firm stalks with no discoloration.

Other FAQs about Onions which you may be interested in.

How long cut-onion last in the fridge?

How to tell If an onion is bad?

How to tell if the onion has spoiled?

When exposed to moisture and heat, onions will start to sprout. The bulb will shrink giving rise to the greens on top.

Sliced, cut or whole onions might develop dark or moldy spots on them due to improper storage. In addition to this, sliced or cut onions will develop a slimy texture when spoiled. Whole onions start to become mushy.

Does eating bad onions make you sick?

Eating a bad onion might not have any serious effects. Your stomach might act up a little and obviously, it will taste bad. But food poisoning from eating a bad onion is a rare case.

Health benefits of onions

Rich source of fiber

Onions are rich in fiber especially the soluble fiber called fructans that is considered a prebiotic fiber. They feed the healthy gut bacteria that results in the formation of Short Chain Fatty Acids SCFA, which improve gut health, reduce inflammation, and prevent cancer.

Good source of Vitamins and minerals

Onions are a good source of certain vitamins and minerals like Vitamin C, Vitamin B9 which is also called Folate, vitamin B6 and potassium. Vitamin C has excellent anti-oxidant properties. Folate and Vitamin B6 are essential for metabolism and Erythropoiesis. Potassium helps maintain fluid balance in the body.

Controls blood sugar

Onions have been found to prevent Diabetes type1 and 2 by regulating blood sugar levels.

Improves bone health

Onions have been linked to promote Bone mineral density and prevent bone deterioration. This helps prevent osteoporosis in older adults.

Contains anti-oxidant compounds

Anthocyanins present in onions act as anti-oxidants and give onions their purple or red color.

Reduces risk of heart diseases

A flavonoid compound, called Quercetin, present in onions control blood pressure and reduces the risk of heart-related disease. 


In this article, we answered the question “How to store sliced onions?”, and how to tell if the onion is bad?


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