How to cook
Cut the onions into thin slices and divide into separate crescents. Heat the oil in a pan and put the onions to fry until they catch a tan.
Add the sugar and mix. As soon as they begin to caramelize, add the balsamic vinegar, a little hot water (2-3 tablespoons) and let it evaporate. Add water 2 more times, and finally fry until the complete evaporation of the liquid.
Allow the onions to stew under the lid after removing from the heat. Finally, sprinkle with salt to taste.