Heat oil on medium high heat
Add onions and cook until soft golden.
Add coriander + cumin powder → stir 10–15 seconds only
Add marinated chicken → seal on medium-high 5–6 minutes
Add water/stock + lemon zest and mix
Cover & simmer 18–20 minutes until chicken is tender
Uncover and add crushed pepper + garam masala
Switch OFF heat THEN add lemon juice + sugar
Rest 5 minutes before serving