In a wide-bottomed pan, melt the butter over low heat. Once melted, add the sugar, garlic and spring onions, which you have previously cleaned (removing the thin skin covering them) washed and soaked in cold water for 30 minutes. Add salt and pepper and deglaze with vinegar. Increase the heat slightly, cover with a lid and leave everything to cook for about 30 minutes. Allow at least ten minutes before serving, allowing them to cool, stirring if necessary. Some variations of the recipe include 80 g of chestnut honey instead of sugar and balsamic vinegar instead of white vinegar.