The executive chef of dine by Peter Gordon at SkyCity answers your cuisine questions.
For such a classic soup it's amazing how many variations there are out there. I've had it made with onions of every hue, but the sweetest of all are red onions, so if that characteristic is something you'd prefer to steer clear of, then use brown or white-skinned onions.
Onions have an innate sweetness, which would seem at odds with their raw state, but by slowly cooking them, usually in a mixture of olive oil and butter, their more subtle and delicious nature is coaxed out.
I'd say that in all recipes an old onion will add a harshness and slightly bitter taste if left to sit around too long. Old onions begin to taste - well - oniony. Newly harvested onions have a lovely freshness and crunch to them, and at this point in their life it is a pleasure to eat them raw. In Turkey they perform an act on them best described as "murdering the onion" in which raw sliced or diced onions are rubbed between your hands with coarse salt for a few minutes before leaving to rest. After 10 minutes they're rinsed under cold running water to remove their oniony characteristics and saltiness, at which point they have an almost apple-y texture and flavour. They are still an onion, but one with no bitterness at all. At this point they appear as a salad's best friend especially if mixed with lots of diced tomatoes, large amounts of sumac, and olive oil - a terrific salad.
It is the slow cooking and therefore caramelising of onions that transforms these eye-watering vegetables into a thing of beauty. And it's also this characteristic that gives French Onion soup it's deliciousness. If you were to simply boil sliced onions in beef stock then you'd be creating something more akin to Vietnamese pho soup. In this, the onion adds a savoury note rather than a sweet one, but the use of sweet spices like cinnamon, star anise, fennel and cloves keeps the savoury character in balance. Both "soups" have the same two key ingredients, beef stock and onions, but yet couldn't be further from each other in final flavour.
I just googled French Onion Soup Recipes and was amazed at the variation on-line out there. Some say to add cognac, others red wine, and some even use sherry.
Like most classic recipes there are a thousand variations, and it would seem that you are free to do whatever you please. All you need bear in mind is that you must cook the onions slowly and for at least 45 minutes until you can squash them between your fingers.
Add the best beef stock you can find. Add a little sugar if they need boosting, and add dry sherry or cognac towards the end if they need de-sweetening. Make sure the croutons are crunchy and use a cheese with age and depth on top. But at the end of the day, just make it tasty and richly flavoured and hope for the best!
* To ask Peter a question, click on the Email Peter link below.