Pour the tomatoes into a blender or food processor and puree until smooth.
Heat the oil in a large skillet or casserole dish over medium heat.
Add the onion and salt and cook, stirring occasionally, until the onions are soft and translucent - about 5 to 7 minutes.
Add the ginger and garlic and cook until fragrant, about 1 minute
Add the garam masala and cayenne pepper, stirring constantly, until fragrant, about 30 seconds.
Add the pureed tomatoes, chickpeas, coconut milk and chopped coriander.
Adjust the salt.
Increase the heat to medium-high - once the mixture begins bubbling around the edges, reduce the heat to low.
Simmer, stirring occasionally, until the sauce thickens, about 20 minutes.
Serve, over steamed rice, sprinkled with more chopped coriander.