Ingredients:

3 pounds lean ground beef
1 cup (packed) crumbled feta cheese
2 teaspoons dried oregano
1 1/2 teaspoons salt
1 1/2 teaspoons ground black pepper
8 large garlic cloves, peeled
1/2 cup plus 1 tablespoon extra-virgin olive oil
Nonstick vegetable oil spray
2 medium red onions, peeled, each cut crosswise into 4 slices
8 hamburger buns
2 large tomatoes, each cut crosswise into 4 slices

Methods:

Break up beef in large bowl.Sprinkle feta,oregano,salt,and pepper over;toss.Divide into 8 portions; form each into 41/2-inch patty,pressing in center to form slight indentation.

Spray grill rack with nonstick spray. Prepare barbecue (medium-high heat). Brush onion with 1 tablespoon oil;sprinkle with salt and pepper. Place burgers and onions on grill. Cover; cook 5 minutes.Turn;cook until onions are charred in spots and burgers are medium-well, about 4 minutes longer.Transfer to plate.Brush cut sides of buns with garlic oil. Place buns,cut side down,on grill; toast about 1 minute.Turn;cook until heated,about 1 minute.

Place burgers on bun bottoms.Top each with onion,tomato,and bun top.