Colorado Lamb and Couscous Crostini

Name: Colorado Lamb and Couscous Crostini
Ingredients: 1/4 cup pine nuts; 1/2 cup beef stock; 1 tablespoon unsalted butter; 1/3 cup couscous; 1 lemon, zested and juiced; 1 small tomato, cut into 1/4-inch dice; 2 tablespoons chopped fresh mint leaves, plus more for garnish; 2 ounces feta cheese, crumbled; 8 ounces chorizo, removed from casing and sauteed until done; 1 small seedless cucumber, peel on, cut into 1/4-inch dice; Kosher salt and freshly ground black pepper; 1 (14-ounce) boneless lamb loin, fat and silver skin trimmed; 1/2 teaspoon ground cumin; 3 tablespoons olive oil, plus extra for grilling; 1/2 cup plain yogurt; Toasted crostini