In a large bowl, combine beef, onion, Worcestershire sauce, Italian seasoning, salt, and pepper. Use your hands to thoroughly mix the spices into the beef.

Separate the beef mixture into 4 roughly equal portions.

Shape each portion into a ball. Then, using the palms of your hands, flatten the ball into a patty. Use your thumbs to smooth the edges of the patty.

Preheat the grill to high.

Cook hamburger patties on high for 4-6 minutes per side (8-12 minutes total). Do not turn patties over until they easily release from the grill. (If the hamburger patties stick to the grill, they are not ready to be turned yet.)

Cook until the internal temperature of the hamburgers measures 160 degrees F.

For cheeseburgers, top burgers with one slice of cheese each in the last 1-2 minutes of cooking.

Remove hamburgers (or cheeseburgers) from the grill. For toasted hamburger buns, turn off grill heat. Place the buns, cut side down, directly on grill grates for 1-3 minutes, until they reach the desired level of toastiness.