Combine the Indian restaurant spice mix, kasoor methi, kashmiri chili powder and salt in a small bowl. This is your spice mix.
Cut up the chilies and tomatoes.
Dilute the tomato paste with enough water to get to the consistency of passata.
Heat your frying pan (don't use non-stick) briefly over medium heat. Add 3 Tbsp vegetable oil. Use all the oil specified. It's important.
When the oil starts to shimmer add the cinnamon bark and green cardamom. Cook until you see little bubbles form around the whole spices.
Add the garlic and green chilies and cook until the garlic just starts to turn golden.
Add the garlic ginger paste. Cook it, stirring constantly, until it stops sputtering.
Turn down the heat to medium low and add the spice mix you prepared above. This is a critical step so really pay attention here. Stir it constantly for about 30 seconds. If it starts to darken lift the pan off the heat. You want the spice mix to cook in the oil but not burn.
Turn the heat up to medium high. Add the diluted tomato paste and stir until bubbles form (the oil will likely separate). This takes around 30 seconds to one minute depending on the heat.
Add the cilantro leaves and stems. Cook for around 15-20 seconds.
Add 3 oz of curry base. Stir until bubbles form (little craters really), around 30 seconds. Watch the edges of the pan. The curry can stick here.
Now add 6 oz of curry base and stir briefly. Let it cook until the bubbles form again. This takes 1-2 minutes.
Add the rest of the curry base and let cook until the bubbles form again. Turn the heat down to low, add the garlic pickle and then the pre-cooked chicken.
Let the curry simmer for about 5 minutes. If it gets too thick add a bit more curry base. Don't add water.
Add the cherry tomatoes and cook until the tomatoes are just warmed through. Garnish with a bit of chopped fresh coriander if you like and serve.