Heat a gas grill to medium-high or prepare a charcoal fire.
In a large bowl, whisk together the miso, soy sauce and ginger. Add the ground turkey, scallions, breadcrumbs and black pepper. Gently but thoroughly mix together. Shape into 4 patties, each about 3/4 inch thick.
To oil the grill grates, dampen a folded paper towel with vegetable oil, hold it with tongs and rub it over the grates.
Grill the burgers until well browned on the underside, about 4 to 5 minutes. With a metal spatula, turn the burgers over carefully. Grill for another 4 to 6 minutes, or until the burgers reach 165 F at the thickest part.
Meanwhile, toast the buns at the edge of the grill. Season the burgers with salt. Dress the burgers with condiments and vegetables as desired.