Peshawar-style lamb curry

Ingredients

• 1 libra 5 ounces/600g Boneless Shoulder or Leg of Lamb, cut into 1 inch cubes
• 4 tablespoons Sunflower Oil
• 1 Cinnamon stick
• 5 Green Cardamom pods, bruised
• 5 Cloves
• 2 Bay Leaves
• 1 Large Onion, finely chopped
• 2 teaspoons Ginger Purée
• 2 teaspoons Garlic Purée
• 1 tbsp Tomato Purée
• 1 teaspoon Ground Turmeric
• 1 teaspoon Ground Coriander
• 1 teaspoon Ground Cumin
• 125g/4 ounces Thick Set Natural Yogurt
• 2 teaspoons Corn Flour
• 1 teaspoon Chilli Powder
• 150ml/5fl ounces Warm Water
• 1 tablespoon Chopped Fresh Mint Leaves
• 2 tablespoons Chopped Fresh Coriander Leaves