In a large sauté pan over medium-high heat warm the oil. Add the cumin seeds and onion. Sauté until the onions are lightly golden (~7-8 minutes). Add the garlic and ginger and sauté for another minute, until aromatic.
Add all the ground spices and sauté for 1-2 minutes. Now add the chopped tomatoes, tomato paste, mix well and cook further for 5 minutes.Add the chicken and sauté until it starts to get opaque, about~3 mins.
Add the red and green bell peppers, cubed onion petals (if using), green chili pepper and salt. Sauté for another 4-5 minutes, until the bell peppers have softened, but still crunchy to your liking. If the curry is looks dry or lost all its moisture, add about 2 tbsp-1/4 cup of water and sauté to desired consistency. Take it off the heat. This curry is not meant to be very saucy.
Squeeze in the lemon juice, garnish with cilantro and julienned ginger. Serve with roti, naan, or rice.