Tandoori-Style Chicken Burgers

INGREDIENTS

• 1 1/2 pounds (4 to 5) boneless, skinless chicken thighs, cut into rough chunks
• 4 scallions, thinly sliced
• 3 tablespoons chopped fresh ginger (from a peeled 2-inch piece)
• 2 tablespoons freshly squeezed lemon juice (from 1 lemon)
• 1 tablespoon paprika
• 2 teaspoons ground cumin
• 1/2 teaspoon ground cardamom
• 1/4 teaspoon cayenne pepper
• Coarse salt and ground pepper
• Vegetable oil, for grates
• 4 (6-inch) whole-wheat pitas
• 1 cucumber (8 ounces), halved lengthwise and thinly sliced on the diagonal
• 1/2 cup fresh cilantro sprigs
• Cumin yogurt sauce (see recipe below)
• Watermelon slices (optional)