Lamb Burger with Herbed Yogurt and Pickled Onions recipes

Name: Lamb Burger with Herbed Yogurt and Pickled Onions recipes
Ingredients: 1 cup whole Greek yogurt; 1 teaspoon finely grated lemon zest; 2 tablespoons finely chopped cilantro; 2 tablespoons finely chopped flat-leaf parsley; 2 tablespoons finely chopped mint; 2 tablespoons finely chopped oregano; kosher salt; ¼ cup sherry vinegar; 1 tablespoon honey; 1 small red onion, very thinly sliced; 1¼ teaspoon kosher salt and ½ teaspoon freshly ground black pepper, plus more to taste; 1½ pounds ground lamb; 1 teaspoon ground cumin; 2 tablespoons olive oil; 4 hamburger buns, split in half