Place peppercorns into a dry frying pan and cook over a low-medium heat until fragrant. Remove peppercorns then place in a mortar and pestle. Allow to cool then crush to a medium texture.
Rub lamb with olive oil and sprinkle both sides evenly with mixed pepper. Add lamb to a preheated frying pan and cook over medium-high heat for 2-3 minutes each side. Remove and season with salt. Cover lamb with foil and allow to rest for 2 minutes before slicing.
To make yoghurt dressing, combine yoghurt, coriander, lemon rind, cumin and salt in a bowl.
Serve sliced lamb on a bed of mixed salad leaves, roasted pumpkin and sliced red onion. Top with a generous dollop of yoghurt dressing.