1. Peel the onions and slice in half down the pole.
2. Slice crossways into thin slices.
3. Heat enough olive oil in a pan over medium heat to coat the amount of onions you are going to cook.
4. Add the onions, toss them in the oil and sprinkle with a pinch of salt.
5. You can cook them over medium heat in the beginning as they release liquid. Stir them intermittently.
6. As they have given off most of their liquid, you need to reduce the heat to low/very low and stir more frequently.
7. Be patient and wait for them to develop a golden brown or even deeper brown color. You can taste occasionally to see if they have developed the amount of sweetness and caramelization you like.
8. If they are sticking and you are getting a lot of brown bits stuck to the pan you can deglaze with a bit of water, wine or vinegar, but I did not need to do this.
9. When they are done to your liking, portion and freeze for up to 2 months. You can portion in baggies or any other freezer safe container but another good idea is to portion into muffin tins and freeze, then put all your muffin size portions in a big ziploc bag. The quantity will be dramatically less than what you started with.
The overall idea is to cook them slowly over low heat - you are NOT trying to brown them quickly or stir fry them.