Combine the tandoori paste and yogurt in a sided dish just large enough to hold the lamb in a single layer. Add the lamb and turn to coat. Cover and marinate in the fridge for 4 hours, or overnight, turning occasionally.
Make the chutney by combining the remaining ingredients in a bowl; cover and set in the fridge until the lamb is ready. Preheat your barbecue or indoor grill to medium-high; lightly oil the surface. Grill the lamb 3-4 minutes per side, or until the desired doneness is achieved. Divide the lamb among serving plates. Top with a spoonful of the chutney, garnish with mint sprigs and serve.