Heat the oil in a saucepan over a medium heat. Saute the onion and garlic for 15-20 minutes until golden and sweet, stirring now and then.
Add the thyme and fresh mushrooms and cook for another 15 minutes or until the moisture in the mushrooms has evaporated. Season with salt and pepper.
Add the stock or water, the fino sherry , and the dried porcini and their juice to the pan. Bring to the boil and simmer for 5 minutes.
Meanwhile pound the almonds in small batches in a pestle and mortar or in a blender until as fine as possible. Stir the almonds and parsley into the soup then check seasoning and serve.