Soak the beans in water overnight. Boil them in plenty of unsalted water for 1 hour, until they are soft. Mash them with a fork, pound them in a pestle and mortar or press them through a sieve. Add the olive oil, the finely chopped herbs and garlic and the seasoning. If the puree is too stiff add some lemon juice, water or more oil. Chill and serve with toast.