Combine oil, lemon juice, garlic and rosemary. Remove half and reserve for dressing. Pour remaining mixture over lamb, refrigerate and marinate for 1 hour.
Cook lamb on a preheated BBQ or chargrill plate for 6-8 minutes on both sides or until cooked to your liking. Rest for 5 minutes before slicing.
Arrange Edgell Four Bean Mix, spinach and onion on a serving platter. Add water and sugar to the reserved dressing. Serve salad topped with warmed sliced lamb, drizzled with dressing.