1.Make citrus dressing by combining juices and oil in a small bowl.
2.Combine 2 tbsp of the dressing, sumac and lamb in medium bowl.
3.Cook lamb on heated oiled grill plate, uncovered, until cooked as desired. Cover lamb; stand 5 minutes, slice diagonally.
4.Meanwhile, boil, steam or microwave peas until just tender; drain.
5.Place peas in a large bowl with chickpeas, capsicum, onion and ½ cup of the remaining dressing. Toss gently to combine.
6.Serve lamb on salad; drizzle with remaining dressing.