Tangy feta cheese is the surprise filling inside these juicy grilled beef burgers served on toasted Kaiser rolls.
Preheat grill to medium heat. Shape meat into 8 thin patties. Cover each of 4 of the patties with 1 tablespoon feta cheese; top with second patty. Pinch edges of patties together to seal.
Place on grill. Grill 7 to 9 minutes on each side or until cooked through.
Fill rolls with patties.