When the butter and oil are bubbling in the skillet, add the onions andd saute over moderate heat for about 10 minutes, rolling the onions about so they will brown evenly. Be careful not to break the skins.
Pour in the liquid and season to taste. Wrap the herbs in cheesecloth and add the herb bouquet.
Cover and simmer slowly for 40 to 50 minutes until the liquid has evaporated. Remove herb bouquet and serve them as they are or in another recipe.