Rinse quinoa; drain well. In small saucepan over medium-high heat, bring quinoa and water to boil. Reduce heat to low; cover and simmer 13 minutes, or until liquid is absorbed, stirring occasionally. Spread cooked quinoa on baking sheet to cool. Stir in 1/4 cup hazelnuts. Set aside.
Heat oven to 450° F. Brush racks of lamb lightly with 1 teaspoon oil. Sprinkle with 1 teaspoon sea salt and pepper. Coat lamb with quinoa mixture, pressing firmly to adhere. Place lamb on roasting rack in foil-lined, shallow roasting pan. Drizzle with 2 teaspoons oil.
Roast 20-25 minutes, or until desired doneness.
To make Mint Pesto: In small bowl, mix remaining oil, remaining hazelnuts, lemon juice, mint, garlic powder and remaining sea salt until well blended. Stir 1 teaspoon pesto into yogurt.
To serve: Carve lamb into chops. Drizzle with remaining pesto. Serve with yogurt sauce.