You can watch my video tutorial on this at How to make Perfect Caramelised Onions.
Caramelised Onions – soft, syrupy, sweet and almost nutty with so many possibilities! In sandwiches, on salads, tarts, pizza, canapé topping, the list is as lengthy as your imagination.
While cooks may differ slightly in their approach, the general rule in caramelising onions is the same: sliced onions cooked slowly and on low heat. I tend to lean towards medium low – low heat and go for a total of 45 minutes on the hob. The result? Sheer heaven!
Caramelisation is a chemical process in which the sugars are heated and encouraged to break down to form new compounds which give us that signature caramelised brown colour and sweet aroma. In caramelising onions, we have another action coming into play and that’s the Maillard reaction, in which the sugars in the onions react with the small amount of proteins present in the onions. There are a couple of things we can do to aid the whole process, not so much in speeding it up but more of an enhancement of the final product. But more of that later.
Butter or olive oil? Both!
Butter, to me, is essential in this recipe, to give that all important nutty flavour at the end. But butter alone, always runs the risk of your onions browning too quickly, so we add a little olive oil to the mix to bring down our smoking point.
Back to the caramelisation. There are two things you can do to aid the caramelisation.
1. Add a pinch of sugar right at the start, immediately before you add the onions, no need to stir the sugar in before adding the onions. This will enhance the final sweetness and colour.
2. Add a pinch of sodium bicarbonate along with the onions. As mentioned before, when heated, the small amount of proteins reacts with the sugars in the onion and we get a Maillard reaction. Pronounced May-Yar (silent r), not Mel-Lard! There are many factors that affect the Maillard reaction but as far as we’re concerned here, heat and pH are the two that we can control.
Now, we don’t want to change the heat because low and slow, remember? That leaves us with the pH to play with. The more alkaline (higher pH value) the mix, the quicker the reaction. So what can we do? Add a pinch of bicarbonate soda, of course. Not only will this give you a darker shade of onions, but the onions will also be softer as the pectin reacts to the higher alkaline level and weakens. Simply put, the pectin is what holds the onion’s cell walls together – think crumbling pillars.
Bear in mind, these are optional extras. I don’t bother with the sodium bicarbonate and only occasionally bother with the sugar. In the video here, I’ve not gone with either.
Now, I would love to hear from you, comments are back in business in LinsFood after a few years!