Heat 1 tablespoon of oil in a heavy skillet or kadhai over high heat. Add the onion petals and bell pepper strips. Stir-fry for 3 minutes until the edges are lightly charred but the vegetables remain crisp. Remove them from the pan and set aside.

Reduce the heat to medium. Add the remaining 1 tablespoon of oil to the same pan. Add the cumin seeds and let them sizzle for 30 seconds. Add the finely chopped onion and cook for 5 minutes, stirring occasionally, until they turn translucent and light golden.

Stir in the ginger-garlic paste and slit green chilies. Cook for 1 minute until the raw smell disappears. Add the turmeric, Kashmiri chili powder, coriander powder, and salt. Stir quickly to coat the onions and cook the spices for 30 seconds.

Add the pureed tomatoes and cook for 5 minutes, stirring frequently, until the moisture evaporates and you see oil starting to separate at the edges of the tomato paste.

Add the chicken strips to the tomato base. Turn the heat to medium-high and stir-fry for 4 minutes until the chicken pieces turn white on the outside and are well coated in the spices.

Lower the heat to medium-low, cover the pan, and let the chicken cook in its own juices for 5 minutes. Remove the lid and check the thickest piece of chicken with an instant-read thermometer. It must register 74°C (165°F) and the meat should no longer be pink in the center.

Stir in the vinegar, garam masala, and the reserved seared bell peppers and onions. Toss everything together over medium-high heat for 2 minutes so the vegetables warm through and absorb the sauce without losing their crunch. Garnish with fresh coriander leaves and serve immediately.