1) To make the sauce, heat the coconut oil in a large skillet over a medium-low heat and add the ginger. Saute for 30 seconds and then add the spices and cook for 10 seconds. Add the tomatoes and cook for 3 minutes, stirring well. Pour in the coconut milk and simmer for about 15 minutes, until the sauce is thickened. Taste for seasoning and add salt and pepper if necessary.
2) For the salmon, heat the coconut oil in a non-stick pan or cast iron skillet over a medium-high heat. Season the salmon fillets with the coriander powder and a pinch of salt and pepper and then sear them on each side for 7 to 8 minutes, until they are just cooked through. Put salmon on a plate and ladle some sauce over it.