Directions

1. Stir together the yogurt, ginger, cumin, 1/4 teaspoon cayenne, and 1/2 teaspoon salt in a 9-by-13-inch baking dish.
2. Starting on one long side, cut each chicken breast almost in half horizontally, stopping about 1/2 inch before reaching the opposite side. Open each breast like a book.
3. Add chicken to marinade and turn to coat. Cover with plastic wrap. Refrigerate at least 1 hour or up to 8 hours.
4. Preheat broiler. In a small bowl, toss together red onion, cucumber, cilantro, lime juice, remaining 1/4 teaspoon cayenne, and pinch of salt.
5. Transfer chicken to a broiler pan. Discard marinade. Broil chicken, rotating pan once, until cooked through, about 10 minutes. Top with cucumber mixture.