Coconut and tamarind chicken curry

Name: Coconut and tamarind chicken curry
Cuisine: Asian, Indian
Ingredients: 3 onion, chopped into rings; 400g coconut milk; 600g chicken thigh fillets, cut into 3cm x 3 cm pieces; 10 curry leaves (I pick up dried ones from Indian grocers or dry my own. If you can’t find any don’t panic. They are not essential); 1 dried red chilli, finely chopped; 1 tbs coriander seeds, crushed in a pestle and mortar; 1/2 tsp turmeric powder; 1/2 tsp cinnamon powder; 1/2 tsp coriander powder; 1 tsp tamarind paste (I use Sainsbury’s own brand); 1 tsp sugar; 6 cloves of garlic, minced; 1 inch ginger, grated; 1 cinnamon stick (not essential); 1 tsp salt; 2tbs rapeseed oil; 2tsp garam masala; 1 tsp cumin