Step 1: Marinate the Chicken — Mix the yogurt, ginger garlic paste, lemon juice, tikka paste, cumin, coriander, turmeric, and salt into a smooth paste. Add the chicken strips and toss until well coated. Cover and marinate for at least 15 minutes at room temperature, or up to 2 hours in the refrigerator.

Step 2: Sear the Chicken — Heat 2 tablespoons of oil in a karahi or large wok over high heat until shimmering. Add the marinated chicken in a single layer (work in two batches if needed) and stir-fry for 5–6 minutes until lightly charred at the edges and nearly cooked through. Remove to a plate.

Step 3: Build the Sauce Base — Lower the heat to medium. Add the remaining oil, then the finely chopped onion; cook 4–5 minutes until soft and lightly golden. Stir in the ginger garlic paste and sliced green chili; cook 1 minute. Add the tomato paste and cook 2 minutes until darkened. Stir in the ketchup, soy sauce, Kashmiri red chili powder, garam masala, white pepper, and water. Simmer 3–4 minutes until slightly thickened and glossy.

Step 4: Combine Chicken and Sauce — Return the seared chicken (with any juices) to the pan. Simmer on medium heat for 4–5 minutes until cooked through (165°F / 74°C) and the sauce coats every strip.

Step 5: Add the Peppers and Julienned Onions — Stir in the julienned onion and all three capsicum strips. Toss and cook on high heat for just 2–3 minutes — the vegetables must stay bright, crisp, and slightly charred at the edges, never soft.

Step 6: Finish and Serve — Take the pan off the heat. Scatter over fresh cilantro and squeeze over a little lemon juice. Serve immediately while the peppers are still crunchy.