Leftover lamb curry

Name: Leftover lamb curry
Prep time: 10 min
Cook time: 1 h 30 min
Total time: 1 h 40 min
Cuisine: Indian
Ingredients: 2 onions roughly chopped; 1 large garlic clove chopped; 1 thumb sized piece ginger peeled and chopped; 2 tbsp oil; 4 tbsp medium curry paste; 400g can chopped tomatoes; 1 red chilli halved and seeds removed; 1 cinnamon stick; 200ml lamb stock; 500-700g leftover roast lamb chopped into large chunks; 1 small bunch of coriander roughly chopped; cooked basmati rice naan bread and natural yogurt, to serve