01 - With a sharp knife, create several deep slashes in the chicken thighs and drumsticks for improved marinade absorption.
02 - In a large mixing bowl, combine Greek yogurt, lemon juice, vegetable oil, ginger-garlic paste, chili powder, ground cumin, garam masala, turmeric, ground coriander, salt, and chopped green chili if extra heat is desired. Whisk thoroughly until smooth.
03 - Submerge the scored chicken pieces into the marinade, ensuring each is fully coated. Cover and refrigerate for at least 4 hours, preferably overnight for optimal flavor development.
04 - Preheat grill to medium-high heat or set oven broiler to high. Lightly brush grill grates or broiler rack with vegetable oil to prevent sticking.
05 - Remove chicken from marinade, allowing excess to drip off. Grill chicken pieces for 5 to 7 minutes per side, turning occasionally, until nicely charred and internal temperature reaches 165°F (74°C).
06 - Transfer grilled chicken to a plate and let rest for 5 minutes. Plate with lemon wedges, sliced red onions, and fresh cilantro leaves before serving hot.