Simmer potatoes in a large saucepan of water for 15 minutes or until tender. Drain and set aside.
Meanwhile, stir yoghurt, mustard, half the capers, 1 tbsp olive oil, lemon zest and juice, salt, and half the dill in a small bowl.
While potatoes are hot, stir through dressing until evenly coated. Transfer to a serving platter and scatter with parsley, macadamias, saltbush (if using), and remaining capers and dill.