1.Preheat oven to 220°C.
2.Make anchovy butter: Beat butter in medium bowl with electric mixer until soft; beat in remaining ingredients, season to taste. Form into log, roll in plastic wrap; refrigerate until firm.
3.Combine sauce, garlic, rosemary and 2 tablespoons of the oil in small bowl; rub all over beef. Place beef on oiled wire rack over baking dish; pour in enough water to half fill the dish.
4.Roast beef about 45 minutes or until cooked to your liking. Cover beef loosely with foil; stand 10 minutes before slicing thickly.
5.Boil, steam or microwave beans until tender; drain.
6.Heat remaining oil in large frying pan; cook mushrooms, stirring, over medium heat, until tender.
7.Combine mushrooms, beans and chives in large bowl; season.
8.Divide bean mixture among serving plates; top with beef and slices of anchovy butter.