Balsamic Beef Kabob Sandwiches

Directions

• Mix first four ingredients; stir in 1/4 teaspoon pepper and 1/8 teaspoon salt. Toss with beef; let stand 20 minutes.
• Cut each onion into eight wedges; thread onto metal or soaked wooden skewers. Thread beef strips, weaving back and forth, onto separate skewers.
• Grill onions, covered, over medium heat until tender, 5-7 minutes per side. Grill beef, covered, over medium heat until desired doneness, 3-4 minutes per side. Grill flatbreads until lightly browned, 1-2 minutes per side.
• Toss tomatoes with the remaining pepper and salt. Remove onion and beef from skewers; serve on flatbreads. Top with tomatoes.