You need to start with at least two onions. At the outset this might seem like a lot, the quantity shrinks and just about halves by the time you get to the finished product. Cut the onion in half, I cut the root end of the onion off , this makes the slices separate easily, then cut into thin even slices. Discard the end pieces if you like, these bits seem to take a long time to cook down and often end up developing a squeaky texture at the end. Melt some butter in the pan and add a splash of olive oil to stop the butter from burning. Add the onions to the pan and give them a stir to coat them with the butter. You need to keep the temperature on a medium heat until the butter has melted, but once the onions start to sweat down turn the heat down to low. Stir frequently to ensure the onions don’t start to brown or catch on the bottom. Don’t forget it’s important to stir frequently, you want to caramelise the onions, NOT brown them. Add some salt, you need to go by taste, you can always add some later if you need more, but for this quantity of onions, approx. 1/2 tsp is a safe amount to add. Give the onions another stir. After a short while and a bit of stirring you will notice that the onions are starting to turn a beautiful amber colour, don’t get lazy though, it’s still important to keep stirring frequently and keep that temperature low. Be patient. By the time they get to this point I added some brown sugar, you probably don’t need to as they develop that nice sweet flavor, but I wanted mine nice and sweet for my bread. I added some wholegrain mustard for good measure, yum! If the pan starts to dry out you could deglaze the pan with a splash of water, wine or vinegar and force all that yumminess back into the onions again. These are starting to look done, it’s your choice at this point if you want to push them a little bit further and develop the flavor and color more or not, it probably depends on what use you have for your onions. At this point the onions have probably been in the pan for around 30 minutes on a nice slow cook. So it was at this point that I took them off the heat, and as you can see the quantity has shrunk to almost half the size. Voila!! These are best eaten on the day of cooking, in saying that though they will keep in the fridge for a few days. I would suggest adjusting the amount to fit your purposes on the day rather than keeping some for future use, as they never taste the same as they would on the first day. Happy cooking!