Boil the potatoes in plently of salt water and keep warm.

Soak the saffron in a splash of boiling water and then place it in a blender along with the mustard, vinegar and a seasoning of salt and pepper, blend this mixture and then add the oil in a slow steady. Slice the potatoes and arrange on plates and top with the anchovy, parsley and tomato. Finally drizzle over the dressing.