Pistachio-Encrusted Rack of Lamb

Ingredients

• 3 (1-ounce) slices day-old white bread
• 1/3 cup finely chopped pistachios
• 1 1/4 teaspoons grated lemon rind
• 2 1/2 tablespoons finely chopped fresh parsley
• 1/4 cup lemon juice
• 3/4 teaspoon salt, divided
• 1/4 cup finely chopped fresh chives
• 1/4 cup finely chopped fresh mint
• 2 1/2 tablespoons Dijon mustard
• 2 garlic cloves, minced
• 2 (1 1/2-pound) French-cut racks of lamb (8 ribs each), trimmed
• Cooking spray
• Mint sprigs (optional)