Add the potatoes to a pot of water on high heat. Cover and allow to come to a boil, then reduce heat and simmer till tender, about 15 minutes. Then drain.
Meanwhile, add some oil to a large frypan over medium heat. Add the onion and garlic; cook and stir until the onion has softened and become translucent, approximately 5 minutes.
Add the cumin, cayenne pepper, curry powder, garam masala, ginger and salt; cook for a further couple of minutes as the spices become fragrant.
Now stir in the tin of tomatoes, chickpeas, peas and potatoes. Pour in the coconut milk and bring to a simmer. Simmer for around 10 minutes.
Then you are ready to serve. I like to have it with some rice and pappadums.