Step 1

Place cumin and coriander seeds in a cast iron skillet over medium heat and toast until fragrant, about 2 minutes. Transfer to a spice grinder and grind into a fine powder.

Step 2

In a large bowl mix together ground cumin and coriander seeds, chicken, onion, cilantro, garlic, chilies, turmeric, salt, and garam masala until chicken is evenly seasoned.

Step 3

Form 1/4 of meat mixture into a skewer-length cylinder on a baking pan or tray. Press skewer into chicken and form meat around stick. Repeat with remaining meat. Place skewered chicken in freezer for 20 minutes while preparing grill.

Step 4

Light one chimney full of charcoal. When all charcoal is lit and covered with gray ash, pour out and spread the coals evenly over entire surface of coal grate. Set cooking grate in place, cover grill and allow to preheat for 5 minutes. Clean and oil the grilling grate. Remove skewers from freezer and carefully transfer to hot grill. Cook until skewers brown all over and are cooked through, about 3 minutes per side. Transfer to a serving tray, let rest for 5 minutes, then serve immediately.