Sweet potato & coconut curry

Name: Sweet potato & coconut curry
Cuisine: Asian, Indian
Ingredients: 2 tbsp sunflower oil; 1 tsp cumin seeds; 1 large onion, finely chopped; 2 cloves garlic, grated; 20g fresh root ginger, grated; 2 medium tomatoes, chopped; 1 tsp salt; 1 tsp chilli powder; 1 tbsp mild curry powder; 500g Evangeline sweet potatoes, cut into 2cm pieces; 400ml can coconut milk; 235g spinach leaves, chopped; ½ lime, juice; Chapatis, to serve