Onions as Cooking Ingredient

Onions are the ubiquitous straight-man, an essential foil to the cooking of meats, fish, and sometimes vegetables.

When onions start to cook they are sweated, which means giving up some of their moisture. The initial sweating may be done in oil or liquid.

Sweating in Oil

Sweating is normally done in oil or butter. Onions go through three transformations.

Cooked 5 to 10 minutes, they become soft and translucent. This is the general purpose procedure. When foreign cookbooks say "cook until wilted," I take it that they mean this stage.

Cooked in oil or butter 15 to 20 minutes, onions start to become golden, with a rich, characteristic taste. These are sometimes called caramelized onions. These must be reserved for dishes where this taste is desired.

Cooked for 30 to 45 minutes, they become first golden brown, then dark brown, with another distinctive taste. Some Asian and Middle Eastern dishes feature these.

Sweating in Liquid

Sweating in liquid or their own juices is not frequently discussed in cookbooks. Richard Olney provides an exception. In The French Menu Cookbook he proposes sweating the mirepoix vegetables - carrots, onions, and celery - in their own juices, for "purer" taste, on occasions when oil is not needed for binding,.

Nevertheless, although discussion is lacking, a small number of recipes in a wide range of cookbooks use the technique. Generally:

Then why isn’t it used all the time? One answer lies in the necessity for oil to bind the final product together, as for a tomato sauce.

However, if this is the only reason, the vegetables may be sweated in liquid, then steeped in oil.

Steeping

The principle of steeping in oil is nicely illustrated in a Paul Bertolli recipe. (Grilled Tuna and Red Onion Salad, Chez Panisse Cooking). Slivered onions are boiled two minutes, then drained and mixed with olive oil.

This procedure coats the onions with oil, but they are never cooked in oil. Julia Child uses a similar procedure in one of her versions of Provencal green beans, discussed in the green bean section.

Sweat in Oil or Water?

However, binding or liaison is not the whole story. There is also the matter of endurance. If you want onions to be a long distance runner, and survive extensive further cookery, you must sweat them in oil or butter. Sweated in water five or ten minutes, they already begin to fragment

Thus steeping may be used on occasion, but cannot be the general rule.

Many, many recipes, from tomato sauce to Beef Bourguignon, start with onions and carrots in oil, not water. This seems to be a habit. In the light of Olney’s observation, starting them in water, then steeping them after cooking, may often produce an improved result.

Sweating in oil will remain the standard. But we can be alert for situations where the water treatment may be preferable, with later steeping in oil, a procedure that seems to be underused.

Recipes in this book that use this principle include all-purpose tomato sauce, saltsa kima meat sauce, Escoffier’s glazed carrots, green beans provencale, spinach and yogurt. 

By contrast, choucroute is a recipes where you should not even think of anything but oil or butter sweating.

Pressing, Own Juices

For completeness let us add that heat is not even necessary for sweating, as the moisture may simply be pressed out. See Pressed Vegetable Relish in the salad section.

For completeness again, let us say that vegetables may be sweated in their own juices. This is essentially the same as water, since the juices are mainly water.

To Simplify Shopping, Peeling

In our household we have standardized on yellow onions and red sweet onions, always kept in supply. Scallions, shallots, and leeks are reserved for special dishes, simplifying shopping.

Peeling of yellow or red onions is easier if you first cut the onion lengthwise.

To Use in Salads

To remove the raw taste of yellow onions for salads, place slices in ice water and refrigerate for an hour. This can save an emergency trip to the store for sweet Bermuda onions. (From Jaffrey, An Invitation to Indian Cooking).

Paul Wolfert describes another method. Sliver the onion, rub with salt, let stand 4 minutes. Rinse under running water, and squeeze dry. (Eastern Mediterranean Cooking.)

Julia Child has still another method. 

It seems that almost any minor thing you do to onions will take away the raw taste.

Mincing, Thin-slicing

Mincing onions is a genuine chore. So far as I know, they must be minced by hand. Both food processor and hand-held mouli julienne liquefy some of the onions while leaving others in large pieces. I have tried the little set of hand rollers used for mincing herbs but this seems about as much trouble as it is worth.

Fortunately it is seldom necessary to mince onions. Some authors routinely call for minced onions, but this is not necessary. In fact, it is counterproductive for long cooking, as in stews. As Richard Olney has pointed out, the longer the cooking, the larger the chunks should be gradually to release flavor. Minced onions give up their flavor in the first few minutes, and then what?

Thin-slicing is even more tedious than mincing. Fortunately, the mandoline and electric slicer are available for large quantities. See discussion in basics section.

As with mincing, the occasions when thin slicing is genuinely advantageous are rare, not routine.

CARAMELIZED ONIONS

Onions, when well-caramelized, can sometimes alone transform an ordinary dish into something unusual and fine.

They do take some time. Onions will first start to turn golden at 15 or 20 minutes, but really require 30 or 40 minutes for the caramelizing process to become fully developed.

Fortunately caramelized onions may be frozen. Thus a supply can be prepared on the weekend for various later uses.

If you have a crock pot, this is one of the highest and best uses for the device. Method is given below.

I also tried these in the toaster oven. The results fell short of satisfactory. In the dry heat the tip of a wedge would become charcoal, while the middle was barely cooked.

Makes ¼ cup, serves 4 as small garnish

Slice the onions in wedges as thin as you can by hand, or use a mandoline or electric delicatessen slicer.

Warm the oil in the pan and add onions. Toss to coat well with oil.

Simmer gently until done. Toss from time to time. Some onions should turn golden in 15 or 20 minutes. Well-developed caramelizing will take 30 or 40 minutes.

Variation
Add a little sugar at the start.

Slice onions thinly. Place in crock pot and toss with oil. Cook at high setting until onions are caramelized. Stir occasionally. Time should be on the order of [.. 4 to 6.. ] hours.

These are browned, and quite good, but not really caramelized. Our grandfathers ate these with calf’s liver or Salisbury (hamburger) steak.

Gently simmer onions and oil in covered pan until onions are tender, about 15 minutes. Uncover pan, raise heat, and cook 5 minutes or so until onions are brown.