Caramelising onions is a process that can take well over an hour, even though many recipes conveniently omit that fact from their prep time estimates. Thankfully, the folks over at Serious Eats came up with a method that gets the job done in a fraction of the time, and all you need is a little tap water.
If you've ever caramelised onions, you know it can take well over an hour of watching and stirring as the onions cook down. This method however, gives you the same results, and all you have to do is pay close attention and keep some water handy:
As you can see, the key is good stirring and temperature regulation. I use a heavy Le Creuset enamelled cast iron pot, which is great at transferring heat slowly and evenly, preventing the hot and cool spots that are the bane to good caramelisation (a tri-ply stainless steel saucepan would also work well). Every time the fond (that's the browned bits of sugars and proteins that stick to the bottom of the pot) threatens to burn, I add a few tablespoons of water and use a wooden spoon to scrape the bits up. The browned sugars and proteins end up dissolving in the water then spread themselves evenly around the onions.
Kenji does note that the catch here is that the resulting onions aren't quite as cooked down and tasty as they would be if you spent an hour poring over them, but he says they're 90 per cent of the way there and still better than cheats like adding sugar or baking soda to speed up the process, and saves a lot of time in the kitchen.
How to Caramelize Onions in 15 Minutes [Serious Eats]