Broiled Tilapia with Mustard-Chive Sauce

INGREDIENTS

• 2 tablespoons chopped fresh chives
• 1/4 cup plain, full-fat Greek yogurt
• Kosher salt and freshly ground black pepper
• 1/4 cup lemon juice (from 1 large lemon)
• 2 teaspoons agave nectar or honey
• Extra-virgin olive oil, for drizzling
• 4 (5 to 6-ounce) tilapia fillets
• 1 teaspoon Dijon mustard
• Vegetable oil cooking spray