Place the ground turkey in a large bowl. Add the grated onion, Dijon, Worcestershire, garlic, panko, egg, salt, pepper, thyme, and 1 tablespoon olive oil. Use a fork or clean hands to mix just until combined. Overmixing makes the burgers dense.
Divide the mixture into 4 equal portions. Gently form each into a ¾-inch-thick patty about 4 inches wide. Press a shallow dimple in the center of each with your thumb. This helps them cook evenly and stay flat. Place on a plate and chill 10–15 minutes if time allows. Chilling firms them for easier handling.
Heat a large skillet (cast iron works well) over medium heat. Add a thin film of olive oil. When the oil shimmers, place the patties in the pan. Cook 5–6 minutes without moving them until the bottoms turn golden brown. Flip carefully and cook another 5–7 minutes, or until the internal temperature reaches 165°F in the center. The exterior should look browned and the juices should run clear.
Transfer the cooked patties to a plate and let rest 3 4 minutes. Toast the buns lightly. Build each burger with your preferred toppings and serve immediately while hot and juicy.
