Peel and dice the sweet potatoes into small cubes. Finely chop the tomatoes, onions, ginger and garlic. Keep the sweet potatoes in the water to prevent it from blackening, while you prepare the curry base.

Add oil in a stainless steel pan on medium heat. Add cassia or cinnamon stick and the lemongrass to the oil. Cook for about a minute or until the aroma appears.

Add chopped onions, garlic and ginger and cook until the onion appears translucent. Do not cook on high heat or brown the onions.

Add the chopped tomatoes and cook for a further five minutes or until the tomatoes become pulpy. Add Water in small quantities to prevent the ingredients in the pan from burning or sticking to the hot surface.

Add the ground spices - coriander powder, turmeric powder, red chilli powder and salt. Mix thoroughly and cook for a further 2 to 3 minutes.

Add the sweet potatoes and mix it well with the curry base. Cook until the sweet potatoes are done. A knife would go through easily when they are cooked.

Prepare a peanut butter sauce by taking a tablespoon of smooth peanut butter and whisking it with small amounts of water until a sauce-like consistency is achieved.

Add this peanut butter sauce to the dish. This is an optional ingredient for those who have nut allergies.

Now add about a cup of fresh green peas. This adds colour and also boosts the nutritional value of the dish.

Add the coconut milk and stir. Continue to cook for a further 5 minutes with the pot covered with a lid. If the curry appears to be very thick, add a small amount of water.

Optionally add chopped bok choy or any other leafy green such as baby spinach. These greens cook fast so about two to three minutes is enough.

Garnish the dish with fresh parsley or coriander leaves and some large dice of fresh red tomatoes.

This delicious sweet potato curry can be had with a grain of your choice, such as rice, cooked millet or bread, roti or naan.