Put the prawns in a large non-reactive bowl. Mix together the tandoori paste, yogurt and lime juice in a bowl, then season well. Pour over the prawns and toss to coat evenly, then cover and leave to marinate for 8–10 minutes.
Meanwhile, make the mint and yogurt dip. Mix together all the ingredients in a bowl until smooth, then season to taste. Cover and chill until ready to serve.
Thread each prawn on to a small metal skewer, then cook under a preheated medium-hot grill for 6–8 minutes, turning once, or until the prawns turn pink and are cooked through.
Transfer the skewers on to 4 serving plates and serve with the dip and lime wedges to squeeze over.