This is a light, sweet onion soup to make when those big, juicy spring onions accompany fresh fava beans in the farmers’ market. You can make a quick vegetable stock with the trimmings while you’re prepping the ingredients.
In a large, heavy soup pot heat the oil over medium heat and add the onions. Cook, stirring often, until they have softened and begun to darken a little; do not let them brown. Add a pinch of salt, the stock and the bouquet garni. Bring to a boil, add the barley, reduce the heat, cover and simmer 1 hour. Taste and adjust salt. Add freshly ground pepper.
03Remove the bouquet garni and discard. Add the fava beans and continue to simmer for 5 to 8 minutes more. Stir in the herbs. Serve, topping each bowl with the cheese croutons.