Lamb & fresh herb curry

Ingredients

• 1 kg boneless lamb shoulder trimmed, cut into 2-cm cubes
• 450 g or 3 medium brown onions, sliced thinly
• 1 tsp salt
• 1 tsp ground chilli
• 2 tsp fresh ginger, finely grated
• 1 garlic clove, crushed
• 1 tsp ground turmeric
• 2 tsp tamarind paste
• 500 ml water
• 2 tbsp vegetable oil
• 1 bunch loosely packed coriander leaves
• ½ bunch loosely packed mint leaves
• 4 fresh long green chillies, chopped coarsely
• 60 ml lemon juice
• Mint leaves to serve
• Naan bread, warm, to serve