Prepare all your fresh ingredients. Pull small chunks of sausage meat from the casings.
Heat a large pot over medium high heat. Add the oil and fry the sausage meat until they start to colour (roughly 2 minutes).
Add the butter and onion to the pot. Fry for roughly 2 minutes or until the onion begins to become translucent.
Pour in the Verjuice (or white wine), and scrape away at the bottom of the pot until clear.
Add the mushrooms and cook until softened.
Add the flour and stir well to fully incorporate it into the mixture.
Add the stock, water and pearl barley. Season with salt and pepper.
Bring to the boil, then reduce the heat to medium and simmer for 30 minutes. Give the pot a stir every now and then.
After 30 minutes, check the pearl barley is cooked to your liking. Once done, remove from heat and stir through the cream.
Check the seasoning, consistency and creaminess of your soup and adjust according to your taste.
Ladle into bowls, garnish with parsley and serve alongside crusty bread rolls. Grate the Parmesan over the soup, if using.