One-pan rogan josh

INGREDIENTS

• 2 onions , quartered
• 4 tbsp sunflower oil
• 4 garlic cloves , finely crushed
• thumb-size piece fresh root ginger , peeled and very finely grated
• 2 tbsp Madras curry paste
• 2 tsp paprika
• 1 cinnamon stick
• 6 green cardamom , bashed to break the shells
• 4 cloves
• 2 bay leaves
• 1 tbsp tomato purée
• 1kg lean leg of lamb , cut into generous cubes
• 150ml Greek yogurt
• chopped coriander , to garnish