Wagyu beef is available at specialty butcher shops.
Adjust the quantity of salt and pepper to suit your own taste. If you're unsure, season and then fry a small piece of your burger mixture to test for seasoning.
No burger is complete without toppings and a bun, of course. Keep condiments to a minimum: caramelized onions and Comté cheese (which has a nutty taste) are a brilliant combination. As for the bun, you don't want one that fights with the burger and detracts from the nice meaty taste (no whole wheat). Think of it as a background that merely holds everything together. It should have texture, and not be so squishy that it sticks to the meat. My favourite are Ace Bakery burger/sandwich rolls ( acebakery.com).
750 grams (1½ pounds) ground Wagyu beef
1 teaspoon kosher salt (or to taste)
½ teaspoon freshly ground pepper
Preheat barbecue to high. Season beef with salt and pepper. Form into 4 1-inch-thick patties and grill for 5 to 7 minutes a side or until desired degree of doneness.