1. In large mixing bowl, stir together the breadcrumbs, cheese, leek, herbs and seasoning to taste.
2. Separate 1 egg and lightly beat the yolk with the whole egg (reserving the white). Stir the beaten eggs into the breadcrumb mixture.
3. Using hands, divide the mixture into eight and shape into sausages (add little bit of milk or water if needed). Cover and refrigerate for about 1 hour.
4. Lightly whisk the reserved egg white. Coat each sausage in flour, egg and then in breadcrumbs.
5. Heat enough oil for deep-frying in large pan. Lower the sausages into the oil and cook for about 5 min until crisp and brown. Lift out, drain on kitchen paper and serve immediately.