It’s pretty rare that you’ll want to throw raw onion (or garlic) directly into liquid to cook. In fact… pretty much, just don’t do that. Alliums (the onion and garlic family) taste far better when you cook them before adding them to soups or sauces — the rich, sweet taste of slow cooked, browned onions adds depth and fragrance. In some foods, like french onion soup, friggione, or mujadarra, the onions play a starring role. In others, like many north Indian curries, or some classic sauces, they provide a base for stronger flavours. The process takes a little bit of patience and care — but it’s simple. And definitely worth it.
There are a lot of different ways to tweak the basic process of browning or caramelising onions, and you can stop the process as soon as the onions start to turn a light hazel color, or keep going all the way to dark brown, like an onion marmalade. You can do the onions in a dry pan, or add oil, butter or ghee. In the picture above, I’ve gone to an extreme of frying them into caramelly-golden submission.
The basic process works for other allium, like leeks, and shallots. It involves two stages — first, getting rid of most of the water from the onions; second, getting the onions to the desired browness. In small batches, this can be pretty quick. In large batches, it will take a while.
You can use pretty much any onion you like, and I don’t think it makes a whole lot of difference. I’ve gotten into heated arguments with Indian friends on this point, however, who think that the purple onions are by far the best. And I’ll defer to that.
In some regions of India, a spoon of thick onion marmalade goes into most dishes. A friend’s mother used to cook down a full pot of onions every weekend, and use them up through the week. Done in bulk like this, it can take several hours to cook them to a brown paste. But it’s not much work, as long as you take care not to let them burn. And it’s so good.
– Oil, butter, ghee
– Balsamic vinegar
– Wine or beer
Slice the onions. You can either do them in full rounds — but this is more work (unless you use a mandolin) — or half-rounds. Cut the onion in two, from stem end to root end, and slice thinly. For some recipes, you might also use strips, or finely chopped onion. It doesn’t matter much. Try to be at least a little bit consistent in your sizes, because smaller pieces cook a lot faster. But if you’re cooking the onions to marmalade, this won’t matter too much.
If you are doing the onions in oil from the start, you can just put the onions in the pan and start cooking. But if you’re cooking in a dry pan, you’ll want to sweat the onions. Otherwise, you’re liable to end up with a mix of burnt bits and raw bits. So, put the onions in a pot, and put a lid on it. Use low heat, because the onions can stick pretty easily.
After a little while, the onions will start to generate steam, and this steam will cook the onions. Stir them once or twice. Soon, you’ll notice that most of the onions will be starting to get translucent, and softer. You’ll also notice that there’s moisture collecting at the bottom of the pan. Once most of the onions have started to look as if they’re cooking remove the pan lid. For a small batch, this might take just a few minutes, for a large batch, up to fifteen.
Once the onions are cooking, they’ll start losing their moisture. Especially in a large pot, they’ll end up boiling in their own juice. This part doesn’t really smell all that great — remember what I said about not boiling garlic or onion? This is why.
If you’re doing a large batch of onions, you can just leave them alone at this point, on a low heat, and stir occasionally to stop them from sticking (they’ll be increasingly prone to stick as they thicken and dry out). If you’re doing a smaller batch, you can increase the heat and boil it quickly. But you’ll need to stand guard and stir pretty regularly.
You’ll know the onions are done when liquid no longer runs out of them, and you can see the bottom of the pot. The onions should be translucent by now, and very soft.
Be careful at this point, since the onions will burn very easily (burnt onions are bitter). With low heat, keep reducing, and watching the color change. Depending on the recipe, you’ll let them reach a very light golden, or you will keep going until they’re dark reddish brown. This is when they start to smell delicious.
You might add fat at this point, either oil, ghee, butter or lard. This helps avoid sticking, and also helps the onions get brown. You can also take the onions and shallow pan fry them (see below) to get them crispy and delicious (like the onions in the first picture). If you’re making onion marmalade though, you’ll just keep cooking them with no oil, until you get a thick paste.
It’s at the browning stage that you’ll also add other ingredients, like garlic, spices or sugar. It’s also when you’ll add liquids, to reduce them. Just throw the liquid in, and wait for the onions to dry out again. Be careful, again, not to let them burn. Sugar, especially, will make them liable to stick.
Shallow pan frying:
Add oil to a small pan to a depth of about 1 inch (3 cm), and heat it until it’s hot (the onions will sizzle and splatter when you add them).
Working in batches of about 1/2 cup, add the onions. Don’t do too much onion at once. They should have enough room to swim around in the oil, and not turn into an oily-oniony lump. When the onions are dark brown (pull a bit out with a fork), get them out of the oil, and do the next batch. Getting onions out is a bit of art — I use a metal strainer (plastic will melt. I pour the oil through the strainer over a bowl. The onions stay in the strainer, and I put the oil back on the stove.
You’ll need to replenish the oil occasionally. The onions will be soft when they’re hot, but will be chewy and crispy as they cool.
The onions by now are ready to go. They will keep in the fridge for a week pretty easily (if you made extra).