Step 1: Double-Marinate the Chicken — Toss the chicken cubes with 1 tablespoon of the lemon juice, 1 teaspoon of the Kashmiri chili powder, and ½ teaspoon of the salt. Rest 20 minutes at room temperature — this first marinade seasons the chicken to the core. Then add the yogurt, remaining lemon juice, ginger garlic paste, mustard oil, roasted gram flour, remaining Kashmiri chili powder, cumin, coriander, garam masala, turmeric, kasuri methi, and remaining salt. Mix until every piece is thickly coated, cover, and refrigerate 2–8 hours (overnight is best).

Step 2: Prep the Skewers and Heat — If using wooden skewers, soak them in water for 30 minutes so they don't burn. Thread the chicken onto skewers, alternating with onion squares and bell pepper pieces. Leave small gaps between pieces — crowded skewers steam instead of charring. For a twist, use two parallel skewers per kebab so the chicken doesn't spin when you turn it.

Step 3: Grill Method (Smokiest) — Heat a charcoal or gas grill to medium-high (about 450°F / 230°C). Oil the grates. Lay the skewers on and grill 10–14 minutes, turning every 3–4 minutes, until charred at the edges and the chicken reads 165°F (74°C) inside. In the last 2 minutes, baste with melted butter — that's the restaurant shine.

Step 4: Oven Method (Easiest Batch) — Move the top oven rack to 4–5 inches from the broiler and preheat the broiler on high. Line a rimmed baking sheet with foil and set an oven-safe wire rack on top. Arrange the skewers on the rack and broil 12–16 minutes, turning once halfway and basting with melted butter, until deeply charred in spots and cooked through to 165°F (74°C).

Step 5: Air Fryer Method (Fastest Weeknight) — Preheat the air fryer to 400°F (200°C). Cut the skewers to fit the basket if needed, or thread shorter kebabs. Arrange in a single layer with space between them and air-fry 12–14 minutes, flipping once at 7 minutes and basting with butter, until the edges are crisp and charred and the internal temperature hits 165°F (74°C). Work in batches — overcrowding kills the char.

Step 6: Rest and Serve — Rest the skewers 5 minutes — this keeps the juices in the chicken. Slide the chicken and vegetables off the skewers onto a platter (or serve on the skewers for drama), scatter with chopped cilantro, and serve hot with mint chutney, sliced onions, and lemon wedges.