First marinate chicken. For this add 2 tsp red chilli powder, 1 tsp ginger garlic paste, turmeric powder, lemon juice, salt and mix this well.
To this add chopped chicken pieces and mix well. Marinate this for half hour
Heat 6 tsp oil in a pan. Once oil is hot add whole garam masala, then add onions and saute the onions till it gets light brown color.
Add ginger garlic paste and saute till raw smell from ginger garlic goes away.
Add coriander powder, cumin powder and saute for 2 mts.
Now add tomatoes and cook till tomatoes gets fully mashed up with onions. For this cover it and cook for 5 mts.
Add red chilli powder an cook till oil starts loosing out from the spices.
Now add marinated chicken and half cup water and mix all well. Cover it and cook for 10 mts.
After 10 mts open the cover, stir the chicken, cover and cook for another 10 mts.
Once chicken is 80% cooked add garam masala and bell pepper, mix well, cover and cook for 5 to 10 mts till chicken and pepper gets fully cooked.
Kadhai Chicken is ready to serve now!