This burger is dressed up with olive tapenade, grilled zucchini and onions, and fresh spinach. It's chockfull of vegetables and flavor!
Combine yogurt and 1/4 cup tapenade in small bowl. Cover and refrigerate until ready to use.
Combine Ground Beef and remaining 1/4 cup tapenade in large bowl, mixing lightly but thoroughly. Lightly shape into four 1/2-inch thick patties.
Heat grill pan over medium heat until hot. Place patties in pan; cook 10 to 12 minutes until instant-read thermometer inserted horizontally into center registers 160°F, turning occasionally. Season with pepper, as desired. Remove; keep warm.
Add onion and zucchini to grill pan over medium heat; season with salt and pepper, as desired. Cook 5 to 6 minutes or until lightly browned and crisp-tender, turning occasionally.
Spread 1 tablespoon yogurt mixture on the cut side of each bun, then add spinach to bottom bun. Place burger on top of spinach and add 1 tablespoon cheese; top evenly onion, and zucchini. Close sandwiches.
Test Kitchen Tips It’s not a good idea to cut into a steak or burger to see if it’s done. You’ll lose juices and risk drying out the meat. Instead, rely on your thermometer to tell you when it’s done.