My Grandmother's Spicy King Prawn Balti

Ingredients

• 1 lb (450 g) king prawns, peeled and deveined
• 1 tbsp (15 g) lemon juice
• 1 tsp (5 g) turmeric powder
• 1 tsp (5 g) chili powder
• 2 tbsp (30 ml) vegetable oil
• 1 large onion, finely chopped
• 3 cloves garlic, minced
• 1 inch piece of ginger, grated
• 2 green chilies, slit lengthwise
• 1 tsp (5 g) ground cumin
• 1 tsp (5 g) ground coriander
• 1 tsp (5 g) garam masala
• 1 can (14 oz/400 g) crushed tomatoes
• 1/2 cup (120 ml) coconut milk
• Salt, to taste
• Fresh cilantro, for garnish