Tamarind chickpeas

Name: Tamarind chickpeas
Ingredients: 1 tbsp vegetable or sunflower oil; ½ tsp nigella seeds (look for these in supermarkets); 1½ tsp fennel seeds; 1 medium onion, chopped; 400g can chopped tomato; 3 green chillies, seeded and cut into qurters lengthways; 2-3 tsp light muscovado sugar; 1 tsp paprika; 1 tsp turmeric; 410g can chickpeas, drained and rinsed; 1 tbsp tamarind paste; 1 tbsp chopped fresh coriander; half a 250g/9oz bag baby spinach leaves; natural yogurt and chapatis, to serve