Hearty chicken and spinach curry

Ingredients
3 tbsp vegetable oil
1 tbsp mustard seeds
2 green chillies, finely chopped
2.5 clove cm (1in) piece ginger, peeled and chopped
2 medium onions, peeled and roughly but finely chopped
300 g (10oz) potatoes, cubed
2 courgettes, cut into chunks
2 pointed peppers, cut into chunks
1 sweet potato, cut into chunks
100 g (3½oz) split red lentils
1 tsp chilli powder
5 large tomatoes, chopped
400 ml (14fl oz) can coconut milk
400 g (13oz) chicken breasts, cut into strips
150 g (50z) fresh spinach
1 tsp turmeric

Method
Heat oil in a large pan and add mustard seeds. When they pop, add chillies and ginger. Stir for a few minutes then add onions and cook for 3-4 minutes, occasionally stirring. Add potato, courgette, pepper, sweet potato and lentils. Cook for a further 3-4 minutes then add chilli powder and turmeric.
Add tomatoes and cook for 2-3 minutes then add coconut milk and 300ml (10fl oz) water. Stir in chicken. Cover pan and cook for 35 minutes, removing lid for final 15 minutes, until vegetables are tender and sauce has thickened.
Wash spinach, pat dry, and add to curry for just the final 2 minutes of cooking.