Sauté the aromatics (optional but recommended): Heat the coconut oil in a medium frying pan over a medium heat. Add the diced onion and cook for 4–5 minutes, stirring occasionally, until it turns translucent and softens—you'll notice a sweet, mellow smell filling your kitchen. Add the garlic and ginger and cook for another minute until fragrant. This step builds a flavour base that the slow cooker can't quite achieve on its own.

Bloom the spices: Tip in the curry powder, cumin, coriander, turmeric, and cayenne if using. Stir constantly for about 30 seconds. You'll see the spices darken slightly and release a deep, aromatic scent—this is the moment the magic really starts.

Transfer to the slow cooker: Scrape the onion and spice mixture into the slow cooker pot. Add the sweet potato chunks, drained chickpeas, tinned tomatoes, coconut milk, vegetable stock, tomato purée, and salt. Give everything a good stir—you want all those golden-orange sweet potatoes to be coated in the spiced coconut liquid.

Set and forget: Pop the lid on. Cook on HIGH for 4 hours or LOW for 7 hours. About halfway through, you'll notice the kitchen starting to smell incredible—warm, earthy, slightly sweet. That's the sweet potatoes breaking down and releasing their natural sugars into the curry.

Check for doneness: After the cooking time, remove the lid carefully. Pierce a sweet potato chunk with a fork—it should slide in with almost no resistance. The curry will look slightly thicker than when you started, and the coconut milk will have turned a rich, golden-brown colour. If it seems too thin, leave the lid off for the last 30 minutes of cooking to let it reduce.

Taste and adjust: Give the curry a final stir. Taste a spoonful—you're looking for a balance of creamy, spicy, and slightly sweet. Add more salt if needed, or a squeeze of lemon juice to brighten it up. The texture should be thick enough to coat the back of a spoon but still saucy enough to soak into rice.

Serve and enjoy: Ladle the curry into bowls. Scatter over fresh coriander if you're using it. The sweet potato chunks will be tender but still holding their shape, and the chickpeas will have absorbed all those lovely spices. Serve immediately with rice or naan bread.