2 pieces white sandwich bread, crusts removed and cut into 1/4-inch pieces
1/3 cup milk
2-1/2 teaspoons kosher salt
1 teaspoon freshly ground black pepper
3 garlic cloves, minced
1-1/2 tablespoons Worcestershire sauce
2 tablespoons ketchup
3 pounds 80 to 85% lean ground beef
3 scallions, very finely sliced (optional)
8 hamburger buns
Preheat the grill to high heat.
In a large bowl, mash the bread and milk together with a fork until it forms a chunky paste. Add the salt, pepper, garlic, Worcestershire sauce and ketchup and mix well.
Add the ground beef and scallions and break the meat up with your hands. Mix everything together until evenly combined. Divide the mixture into 8 equal portions and form compact balls. Flatten the balls into 3/4-inch patties about 4-1/2 inches across. Form a slight depression in the center of each patty to prevent the burgers from puffing up on the grill.
Oil the grilling grates. Grill the burgers, covered, until nicely browned on the first side, 2 to 4 minutes.
Flip burgers and continue cooking for a few minutes more until desired doneness is reached. Check the internal temperature before removing from the grill, they should be 160°F.
Before serving, toast the buns on the cooler side of the grill if desired.