In a bowl mix together the lean minced lamb with 30ml (2tbsp) fresh mint. Season with pepper and mix well.
Divide into 4 and shape into burgers. Cook on preheated grill or barbecue for 4-6 minutes each side. During the last 1-2 minutes of cooking time top each burger with 25g (1oz) Somerset Brie cheese and return to grill to melt.
Mix together the low-fat natural yogurt with the remaining fresh mint to make the minty yogurt.
Serve the burgers on toasted ciabatta with roasted or barbecued peppers, drizzled with the minty yogurt.