24 (1-inch) pieces red bell pepper (about 1 large bell pepper)
24 (1-inch) pieces yellow bell pepper (about 1 large bell pepper)
1 cup (1-inch) pieces red onion
1½ pounds sirloin steak, cut into 1-inch cubes
8 (7-inch) metal skewers
Garnish: chopped fresh parsley
Instructions
In a large bowl, whisk together oil, salt, parsley, garlic, mustard, lemon zest and juice, oregano, and black pepper. In another large bowl, combine bell pepper and onion. Pour half of oil mixture onto vegetables, tossing to combine. Add steak to remaining oil mixture, tossing to combine. Cover and refrigerate steak and vegetables for at least 2 hours.
Alternately thread steak and vegetables onto skewers. Let stand at room temperature for 30 minutes.
Preheat a large cast-iron grill pan over medium-high heat; spray pan with cooking spray.
Cook kebabs in batches, turning occasionally, until browned and an instant-read thermometer inserted in center of steak registers 130° to 135°, 8 to 9 minutes, or until desired doneness. Transfer to a serving platter, and let stand for 10 minutes. Garnish with parsley, if desired.
Recipe by Southern Cast Iron at https://southerncastiron.com/marinated-steak-veggie-kabobs/