- 7 dried Kashmiri or guajillo chiles, broken into pieces, seeds removed
- 1 (1 1/2)-inch piece ginger, peeled, coarsely chopped
- 4 garlic cloves
- 1/2 cup plain whole-milk yogurt (not Greek)
- 3 tablespoons fresh lime juice
- 2 tablespoons mustard oil (optional)
- 1 tablespoon ground coriander
- 1 tablespoon smoked paprika
- 1 1/2 teaspoons dried mango powder (amchoor; optional)
- 1 1/2 teaspoons crushed dried fenugreek leaves
- 1 1/2 teaspoons garam masala
- 1 1/2 teaspoons ground cumin
- 2 tablespoons vegetable oil, plus more for grill
- 1 1/2 pounds skinless, boneless chicken thighs, patted dry
- Kosher salt
- Place chiles in a medium bowl and pour in hot water to cover. Let sit until chiles are very soft, about 30 minutes; drain. Blend chiles, ginger, garlic, yogurt, cilantro stems, lime juice, mustard oil (if using), coriander, paprika, mango powder (if using), fenugreek leaves, garam masala, cumin, and 2 Tbsp. vegetable oil in a blender until smooth. Transfer marinade to a large resealable plastic bag. Season chicken generously with salt and add to marinade. Seal bag and turn to coat chicken. Chill at least 2 hours.
- Let chicken sit at room temperature 1 hour before grilling.
- Prepare a grill for medium heat; oil grate. Remove chicken from marinade, letting excess drip back into bag, and grill, turning every minute or so, until beginning to char in spots, 8–10 minutes total. Transfer to a platter and let rest 5–10 minutes before serving.
- Chicken can be marinated 12 hours ahead. Keep chilled.