Preheat the grill to medium-high heat, aiming for an ambient temperature of 400°F (204°C).

In a large mixing bowl, combine panko breadcrumbs and milk. Allow to sit for 2 minutes until a paste (panade) forms.

Add the grated onion, minced garlic, Worcestershire sauce, salt, and pepper to the panade and whisk to combine.

Add the ground turkey to the mixture. Incorporate gently by hand until just combined; do not overwork the proteins as this causes toughness.

Divide the mixture into 4 equal portions (approximately 5 oz each) and form into patties 3/4-inch thick.

Using your thumb, create a shallow indentation in the center of each patty to ensure even cooking and prevent doming.

Clean and oil the grill grates. Place the patties on the grill over direct heat.

Grill for 5 minutes per side, or until the internal temperature reaches a food-safe 165°F (74°C) using an instant-read thermometer.

Transfer the burgers to a plate and allow them to rest for 3 minutes before serving to allow juices to redistribute.