3/4 teaspoon cumin seeds, toasted
3/4 teaspoon coriander seeds, toasted
2 cups whole-milk yogurt
4 garlic cloves, chopped
1 (1 1/2-inch) piece fresh ginger, peeled and chopped
3 tablespoons vegetable oil plus additional for greasing pan
2 tablespoons fresh lime juice
1 1/2 teaspoons salt
3/4 teaspoon ground turmeric
1/2 teaspoon garam masala (Indian spice mixture)
1/2 teaspoon black pepper
1/4 teaspoon cayenne
5 lb skinless boneless chicken breasts, cut into 1 1/2-inch cubes

Special equipment: 20 (12-inch) wooden skewers
Accompaniments: mango and red pepper chutney and mint raita
Garnish: lime wedges

Pure all ingredients except chicken in a blender until spices are well ground.

Put chicken in a large bowl, or divide between 2 large sealable plastic bags, and add yogurt mixture, stirring or turning to coat. Marinate chicken, covered and chilled (turning occasionally if using bags), at least 4 hours.

Soak skewers in water 30 minutes. While skewers are soaking, bring chicken to room temperature.

Preheat broiler and brush a broiler pan lightly with oil.

Divide chicken among skewers (about 5 cubes per skewer), leaving an 1/8-inch space between cubes, and arrange about 5 skewers across pan. Broil chicken about 4 inches from heat, turning over once, until browned in spots and just cooked through, 9 to 12 minutes total.

Transfer cooked skewers to a large platter and, if desired, cover loosely with foil to keep warm. Broil remaining chicken in same manner. Remove chicken from skewers and serve warm or at room temperature.

Cooks' note:
Chicken can be marinated up to 24 hours.