An iceberg “cheek” is just what it sounds like: a rounded hunk of lettuce.
In a small bowl, whisk the sour cream, buttermilk, herbs, lemon juice, sugar and vinegar. Season the ranch dressing with salt and pepper.
In a medium bowl, add the turkey, scallions, Worcestershire and mustard; season and mix to combine. Form into 4 large, thin patties (thinner in the centers for even cooking).
Heat a large cast-iron skillet over medium high. Add the oil, one turn of the pan. Add the patties and cook 8 to 10 minutes, turning occasionally.
Cut each lettuce head in half along either side of the core, for 4 cheeks. Place 1 iceberg cheek, cut side up, on each dinner plate. Top with the burgers, pickles, tomato and onion. Pour the dressing on top.