How to Make It
Combine turkey, garlic powder, onion powder, dill, and 1 tablespoon each of sour cream, mayonnaise, and buttermilk in a medium bowl. Divide turkey mixture into 4 (5-ounce) portions; shape into 1-inch-thick patties. Sprinkle patties with 1/2 teaspoon each of the salt and pepper.
Heat oil in a large nonstick skillet over medium-high. Add burgers to skillet; cover and cook until bottoms are browned, about 4 minutes. Turn burgers; cover and cook until browned and a meat thermometer inserted in thickest portion registers 165°F, about 3 minutes.
Stir together apple cider vinegar and remaining 3 tablespoons each of sour cream and mayonnaise, 2 tablespoons buttermilk, and 1/4 teaspoon each of salt and pepper in a small bowl. Spread about 1 tablespoon of the mixture on each bun half. Place 1 patty on each bottom half of bun; top each with lettuce, tomato, and red onion slices and other half of bun.