- 1 1/2 pounds lean ground beef
- 3/4 teaspoon plus 1/8 teaspoon salt, divided
- 1/4 teaspoon plus 1/8 teaspoon black pepper, divided
- 2 ounces feta cheese, cut into 4 (1/2-ounce) pieces
- 4 (1/4-inch-thick) red onion slices
- 2 tablespoons extra virgin olive oil, divided
- 4 crusty sourdough bread slices
- 4 teaspoons coarse-grained Dijon mustard
- 12 plum tomato slices
How to Make It
Sprinkle beef with 3/4 teaspoon salt and 1/4 teaspoon pepper; gently mix, and shape into 8 thin patties.
Place 1 piece feta cheese in center of each of 4 patties. Top with remaining 4 patties, pressing edges to seal.
Brush onion slices with 2 teaspoons oil, and sprinkle with the remaining 1/8 teaspoon salt and 1/8 teaspoon pepper. Cook on a lightly greased grill pan or in a skillet over medium-high heat 4 minutes on each side or until tender and slightly charred. Transfer to a plate, and keep warm. Add burgers to pan; cook 6 minutes on each side. Transfer to a plate, and keep warm. Brush bread slices with remaining 4 teaspoons oil. Add to pan, and toast about 1 minute on each side or until lightly golden.
Spread Dijon mustard evenly on 1 side of each bread slice. Top each with 1 onion slice, 3 tomato slices, and 1 burger. Serve immediately.