Be ready. Have your curry base simmering on the stove. Make your spice mix. Chop all the ingredients and have them at the ready. This is going to go very fast. You don't have time to mess around.
Heat a frying pan over medium heat. Add the oil.
When the oil starts to shimmer add the onion and green chilies. Cook, stirring constantly, until the onions just start to brown on the edges. This takes 2-3 minutes.
Add the garlic ginger paste and cook until it stops sputtering, about 1 minute.
Lower the heat to medium low. Add the spice mix. Cook, stirring constantly, for about 30-45 seconds. You want to bloom the spices in the oil. You don't want to burn it. If you burn the spices, start again. There's no fixing it.
Add the diluted tomato paste. Stir to combine and cook for about a minute.
Turn the heat up to medium high. Add 3 oz of the curry base. Stir to combine and cook until it it starts to crater. Little holes will appear. See the guide to Indian curries to understand what this means if you aren't sure.
Add another 6 oz of curry base. Stir to combine and cook until it craters.
Now add the remaining curry base. Cook until it craters and reduce the heat to low. Add the chicken stir to mix. Simmer for about 3 minutes.
Add the fresh chopped tomatoes, cilantro and lemon juice and cook for another 2 minutes or so. If the curry gets too dry add a bit more curry base.
Add the cream. Stir to combine. Serve. Enjoy!