In a bowl, stir together 1/2 cup yogurt (any kind of plain yogurt will do but I love the Greek yogurt best for this), the chopped white parts of 2 green onions, and 1/4 cup fresh mint leaves that have been finely chopped. In a separate bowl, mix 1 lb. ground turkey, 1 1/2 oz. crumbled feta cheese, 1 1/2 tsp. ground coriander, salt and pepper to taste, the chopped green parts of 2 green onions, 2 T. plain yogurt, and 1/4 cup fresh mint leaves, finely chopped. Form this mixture into patties and grill for about 12-15 minutes, turning once, until cooked through and no pink remains inside. Check with your meat thermometer to ensure that it has reached 165 degrees F internal temperature. Warm a couple of whole wheat pitas cut in half on the grill for a couple minutes and serve the burgers inside of them using the yogurt sauce on them. You may want to add other burger fixings such as lettuce and tomato – I also find that some cucumber is a lovely addition here that goes well with these Greek inspired flavours.