Heat the oil in a large karahi or wok over medium-high heat. Add the chicken and cook until lightly browned, 5 to 6 minutes. Transfer to a plate.
Add the garlic, ginger, and green chilies to the pan. Stir for 30 seconds until fragrant.
Cook the Masala:
Add the tomatoes, cumin, coriander, chili powder, and salt. Cook over medium heat, stirring often, until the tomatoes break down and the oil begins to separate, 12 to 15 minutes.
Return the chicken and any juices to the pan. Cover and simmer until cooked through, about 10 minutes.
Finish and Serve:
Uncover and cook for 2 to 3 minutes until the sauce is thick and clings to the chicken.
Scatter over the cilantro and ginger. Serve with lemon wedges and warm bread or rice.
Notes
Reduce the tomatoes until glossy for the best flavor.
A karahi or wok gives the sauce room to evaporate quickly.
Adjust green chili to suit your preferred heat level.