A guide to chopping and sweating onions

I have long admired Leiths School of Food and Wine.

Since its creation, Leiths, based in West London, has retained the values of its founder, Pru Leith — that food should be uncomplicated and unfussy, and that the ingredients should be the star players.

I am delighted to welcome Leiths How to Cook — their first colour-illustrated cookery course book — to New Zealand.

This book takes the reader through every aspect of food preparation and cooking. It explains each culinary skill in detail, and provides easy step-by-step photography. It includes the essentials most cookbooks omit: how to judge when meat is perfectly cooked, how to carve roasts, the correct texture at every stage of pastry, cake and bread making and how to make the perfect pasta and risotto.

There is also great detail on how to prepare every ingredient from scratch such as the section on onions, below. It shows technique that will benefit any cook and answers a very common “ask Peter’’ question on the cooking/sweating of onions.

Onions

Onions are included in many savoury dishes. Yellow onions are the most versatile; white and red onions are valued for their mildness. Shallots and spring onions are members of the onion family too. Shallots are valued for their mild, sweet flavour and are used whole in casseroles as well as sliced and chopped for all manner of dishes. Choose firm onions with a thin, papery skin.

Preparing onions or shallots for slicing or dicing

1. Cut a small slice off the top of the onion so it can stand upright. Trim a little off the hairy part of the root but keep the root intact (as this holds the onion together when you are cutting it).
2. Stand the onion with the trimmed top surface down. Using a large, sharp knife (for onions, a small knife for shallots), cut down through the onion to halve it.
3. Peel each onion half and discard the skin. It is also a good idea to remove the first of the inner pale leaves of the onion as these tend to be leathery and do not break down during cooking.

Dicing onions

1. Halve and peel your onion. With the flat side down and the root end away from you, slice through the onion vertically, towards the root, but not right through it (to keep it intact). For fine dice ensure the cuts are close together.
2. Slice horizontally through the onion once or twice, again not right through the root, but very close to it, keeping the knife slightly angled towards the board for safety.
3. Now move the onion so that the root end is on your left and proceed as for slicing an onion. It may be a little more difficult, but try to hold the onion together in your other hand "clawed'' to protect your fingertips and fingernails.

Sweating onions

This technique describes the cooking process of softening an onion and drawing out its natural sweetness without allowing it to take on any colour. The onions are gently sweated in a little oil or butter. Using a dampened cartouche (a circle of greaseproof paper cut slightly larger than the saucepan) helps the sweating process and seals in the juices.

1. In a suitably sized saucepan, melt a nut of butter or a little oil. Put the onions in the saucepan and place a dampened cartouche on the surface, in contact with the onions. Cover with a tight fitting lid, place over a very gentle heat and allow the onions to sweat. Check the onions occasionally, especially if a lot of steam is escaping. If the cartouche is dry, re-dampen it and return it to cover the onions. If any onions have browned on the bottom of the pan, don't stir them in. Discard them and use a clean saucepan to continue sweating.
2. After 10-15 minutes, check the onions again. They will be ready when they have lost volume and become translucent. If you squeeze a piece of onion between your fingers, there should be no resistance. If you taste a piece, it will have a sweet, milky flavour.

In our Ask Peter series, executive chef Peter Gordon answers your curly culinary questions. If you're stumped over something food-related, send your question to askpeter@bite.co.nz and keep checking in for answers. You can read more on Peter on his website, have a read of his Ask Peter articles or check out his recipes on our site.