Place a saucepan or casserole on a high heat and heat the oil.
When this is very hot, add the onions and garlic and keep turning them from time to time until the edges of the onions have turned dark, this will take about 6 minutes.
Then reduce the heat to its lowest setting and leave the onions to carry on cooking very slowly for about 30 minutes, by which time the base of the pan will be covered with a rich, nut brown, caramelised film.
After that, pour in the stock, season, then stir with a wooden spoon, over a medium heat, scraping the base of the pan well.
As soon as it all comes up to simmering point, turn down the heat to its lowest setting, then go away and leave it to cook very gently, without a lid, for about 1 hour.
Click to start a 60 minute timer
Serve a third of the recipe for one meal, if following our christmas planner. Refrigerate or freeze the remaining portions until needed. Will keep for 5-6 days in the refrigerator.