Clean the grill grates thoroughly and lightly oil them to prevent the burgers from sticking.
If using a charcoal grill, create a two-zone fire by placing the charcoal on one side and leaving the other empty. That way, you can move the burgers to the cooler side if they cook too quickly.
Preheat your grill to medium-high (around 375-400°F/190-205℃). If using a charcoal grill, ensure the coals are evenly lit and glowing.
Lightly mix Wagyu beef, Worcestershire sauce, minced garlic and onions, burger seasoning, salt, and pepper in a large bowl until thoroughly combined. Don't overwork your hamburger mixture—the goal is to combine the ingredients without overmixing.
Divide the mixture into 4-6 equal parts and form into patties. Then, make a slight depression in the center of each patty with your thumb to prevent the burgers from puffing up on the grill. If possible, let the patties firm up in the fridge for at least 30 minutes before grilling.
Place the prepared patties on the preheated side of the grill and cook for about 2-3 minutes per side, undisturbed, before flipping the burger over. That gives the beef time to sear and firm up.
If the surface of the burger is cooking too fast, turn off one side of the gas grill or move the patties on the unlit side, away from direct heat. Wagyu burgers are notorious for flaring up due to their high fat content, so keep a close eye on the grill.
After flipping, cook for 3-4 minutes or more, depending on preference. Also, you can lower the heat at this stage so it cooks evenly.
Keep in mind that cooking time may vary depending on the thickness of the patties and the desired level of doneness. As long as the burger's internal temperature reaches 160°F (70°C), it fulfills FDA recommendations for ground beef food safety.
Optional step: Toast the hamburger buns during the last 2 minutes of grilling.
Remove the burgers from the grill and let them rest for a few minutes.
Assemble your Wagyu burgers with the toasted buns and your favorite toppings like grilled onions, blue cheese, and lettuce. Enjoy!