Place a large wok on medium-high heat and add oil and cinnamon stick.
When the oil is hot, add the pureed onion and saute it until the edges appear to turn golden brown.
Add the ginger-garlic paste and saute for 1 minute.
Add the chicken and leave it undisturbed for 1 minute.
Then give it a stir to flip the pieces and again leave the chicken undisturbed for 1 minute. (Leaving it undisturbed helps to lock in the flavors making the chicken juicy).
Now saute the chicken while stirring frequently until the chicken turns slightly golden brown.
At this point add the following spices- salt, paprika powder, cumin powder, coriander powder, curry powder.
Add 3-4 tablespoons of water (to prevent the spices from burning) and mix well to coat the chicken with the spices.
Add the tomato paste, coconut milk and 1/2 cup hot water.
Stir, cover and reduce the heat slightly and let the chicken cook completely. This may take 10-15 minutes depending on the size of the pieces. Stir at least once/twice to make sure it does not burn.
Once the chicken is cooked completely, add black pepper powder and lemon juice and turn off the heat. Cover and let it sit for 1 minute before serving.
Serve with boiled rice.