1) Dice the onion, and mince the garlic and ginger. Cube the sweet potato and potatoes, dice the carrots.
2) Add about 2 tablespoons vegetable oil to a large sauce pan and saute the onion, garlic and ginger for about 5 minutes over medium heat. Add the rest of the vegetables and saute for another 5 minutes.
3) Pour in the coconut milk and tomatoes and mix in the spices. The amount of spices is pretty much up to you, I usually add more cumin and curry than specified but keep the rest of the measurements the same. Lower the heat a bit and cover the pot. Let it simmer for 30 minutes, stirring often. If you use cilantro, add it to the mixture and cook for another 10 minutes, or until the potatoes are soft.
Let it sit for a few minutes. Serve over rice or with naan bread and enjoy!
Source of recipe: Something I came up with to use a giant sweet potato that was going to go bad.