In a medium bowl, combine beef, onion and Worcestershire. Mix just until combined.
Gently shape into 4 patties, about ¾-inch thick. Using your thumb, create an indent in the center of each burger.
Refrigerate for at least 20 minutes before cooking.
Preheat the grill to medium heat.
Season the outside of the burgers with salt & pepper.
Cook burgers about 4-6 minutes per side or until they reach 160°F.
Rest for 5 minutes. Serve on toasted rolls or buns.