Tip the onion, garlic, ginger, red pepper, sweet potatoes, turkey and chickpeas into a slow cooker. Stir in the curry paste and tomato purée, ensuring everything is well-coated. Pour in the chopped tomatoes and coconut milk, and scatter in the chopped coriander stalks, 1 tsp salt and some ground black pepper. Mix everything to combine. Cook on high for 3 hrs 30 mins, or low for 8 hrs. If you want to add spinach, tip it in 15 mins before the end of the cooking time. Stir well after 5 mins, once it has started to wilt.

Serve the turkey curry with rice, scattered with the chopped coriander leaves, if you like.