Season the chicken. Chop the chicken into bite sized chunks, then add to a small bowl and toss with 1/2 teaspoon of salt. Set aside.
Cook the onion, ginger and garlic. Add 2 tablespoons of butter to a large, high sided frying pan or skillet over medium heat, then add the diced onion. Cook, stirring, for about 5 minutes or until the onion starts to soften nicely and looks translucent (more see-through). At this point, add the 3 crushed garlic cloves and 1 tablespoon of ginger, then stir through the onion for another minute.
Cook the spices and chicken. Add all the spices, and stir through the onion, garlic and ginger for another minute to create a fragrant paste. Add the diced chicken pieces, and spread them out onto a single layer if you can. Let them cook for a couple of minutes on one side, undisturbed, then turn them over and cook for another minute. Add 1/3 cup of passata and 1/2 cup of stock, then stir the chicken through the liquid.
Simmer and reduce the curry. Bring the liquid to a simmer, then pop a lid on your pan (or use a large plate or a wooden board), reduce the heat to low and cook for 5 minutes. Remove the lid, then simmer the curry for another 20 minutes, until the sauce has thickened and reduced nicely into a glossy gravy and the chicken is cooked through.
Make the rice. While the curry is simmering, add 1 cup of rice, 1 1/2 cups of water and 1 teaspoon of salt to a small pot that has a lid. Set over medium heat, and when the water starts to get a little foamy, reduce the heat to low and pop the lid on. Let it cook for 12 minutes, then remove from the heat and keep the lid on until you're ready to serve.
Garnish and serve. Divide the rice between plates, the top with the curry. Scatter over fresh coriander leaves then dig in.