Method
Fry the onion for around 5 mins until soft, then add the mushrooms, garlic, ginger, chilli and spices.
After a minute, add the stock and the sweet potatoes. Cover the pan with a lid and simmer until the sweet potatoes are soft (this takes around 40 minutes).
Once the sweet potatoes are cooked enough, mash a few of them with a fork to break them down to thicken the curry.
Add the coconut milk and cook for a further 5-10 minutes. Taste the sauce and make adjustments to the seasoning/spiciness if required.
Serve immediately with your choice of sides. Rice and naan bread*/chapatis* recommended.